View source for Admiralty Islands campaign

{{Short description|Series of WWII battles}}
{{Featured article}}
{{Use Australian English|date=November 2017}}
{{Use dmy dates|date=November 2017}}
{{Infobox military conflict
| conflict    = Admiralty Islands
| partof      = [[World War II]], [[Pacific War]]
| image       = First Wave at Admiralty Islands.jpg
| image_size  = 300
| caption     = The first wave of US troops lands on Los Negros, Admiralty Islands, 29 February 1944
| alt         = Soldiers walk through long grass. Other soldiers are arriving in landing craft in the lagoon behind them. In the background is a coconut plantation. The sky is overcast.
| date        =  {{Start date|1944|02|29|df=y}}–{{End date|df=y|1944|05|18}} <br /> 80 days
| place       = [[Admiralty Islands]]
| coordinates = {{Coord|2|2|S|147|16|E|region:PG-MRL_type:event|display=inline,title}}
| result      = Allied victory
| combatant1  = {{flag|United States|1912}}<br />{{flag|Australia}}
| combatant2  = {{flagcountry|Empire of Japan}}
| commander1  = {{flagicon|United States|1912}} [[Douglas MacArthur]]<br />{{flagicon|United States|1912}} [[William C. Chase]]
| commander2  = {{flagicon|Empire of Japan|army}} [[Hitoshi Imamura]]<br />{{flagicon|Empire of Japan|army}} Yoshio Ezaki{{KIA}}
| strength1   = 35,000
| strength2   = 4,000
| casualties1 = 326&nbsp;killed<br />1,190&nbsp;wounded<br />4&nbsp;missing
| casualties2 = 3,280&nbsp;killed<br />75&nbsp;captured
| campaignbox = {{Campaignbox New Guinea}}
}}

The '''Admiralty Islands campaign''' (Operation Brewer) was a series of battles in the [[New Guinea campaign]] of [[World War II]] in which the [[United States Army]]'s [[1st Cavalry Division (United States)|1st Cavalry Division]] took the [[Empire of Japan|Japanese]]-held [[Admiralty Islands]].

Acting on reports from airmen that there were no signs of enemy activity and the islands might have been evacuated, [[General (United States)|General]] [[Douglas MacArthur]] accelerated his timetable for capturing the Admiralties and ordered an immediate [[reconnaissance in force]]. The campaign began on 29 February 1944 when a force landed on [[Los Negros Island|Los Negros]], the third-largest island in the group. By using a small, isolated beach where the Japanese had not anticipated an assault, the force achieved tactical surprise, but the islands proved to be far from unoccupied. A furious battle over the islands ensued.

In the end, [[air superiority]] and [[command of the sea]] allowed the Allies to heavily reinforce their position on Los Negros. The 1st Cavalry Division could then overrun the islands. The campaign officially ended on 18 May 1944. The Allied victory completed the isolation of the major Japanese base at [[Rabaul]] that was the ultimate objective of the Allied campaigns of 1942 and 1943. A major air and naval base was developed in the Admiralty Islands that became an important launching point for the campaigns of 1944 in the Pacific. This campaign marked the end of MacArthur's [[Operation Cartwheel]], which was a multi-theater operation conducted to turn the powerful Japanese base of [[Neutralisation of Rabaul|Rabaul]] into a de facto prisoner-of-war camp.

==Background==

===Geography===
[[File:Elkton Plan.jpg|thumb|left|Elkton III Plan, March 1943. The Admiralty Islands are in the top-centre of the map.|alt=Topographic map of Papua New Guinea with arrows indicating an Allied advance along the northern coast towards the Admiralty Islands.]]
The Admiralty Islands lie {{convert|200|mi|km}} north east of the mainland of New Guinea and {{convert|360|mi|km}} west of Rabaul, only two degrees south of the [[equator]]. The climate is tropical, with constant high temperatures and high humidity and an annual rainfall of {{convert|154|in|mm}}. Thunderstorms are common. December to May is the north west [[monsoon]] season, with prevailing winds from that direction.<ref name="Frierson, pp. 6–7">Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 6–7.</ref>

The largest island in the group is [[Manus Island]], which is about {{convert|49|mi|km}} across from east to west and {{convert|16|mi|km}} wide from north to south.<ref name="Morison, p. 432" /> The interior is mountainous, with peaks rising to {{convert|3000|ft|m}} and largely covered with thick [[tropical rainforest]]. The largely uncharted coastline had numerous reefs. The shoreline consisted mostly of [[mangrove swamp]]. 

The third largest island in the province, Los Negros lies to the northeast of Manus, from which it is separated by the narrow Loniu Passage. The island contains two important harbours of its own, Papitalai on the west coast, which connects with [[Seeadler Harbour]], and Hyane on the east coast. The two are separated by a {{convert|50|yd|m|adj=on}} wide sandy spit. Here, the natives built a skidway over which they could drag canoes between the two harbours.<ref name="Frierson, pp. 6–7" /> Los Negros curves horseshoe-like, forming a natural breakwater for Seeadler Harbour, the remainder of which is enclosed by Manus and a series of smaller islands. The main entrance was through a {{convert|1.5|mi|km|adj=on}} wide passage between Hauwei and Ndrilo Islands. Seeadler Harbour is about {{convert|20|mi|km}} across from east to west and {{convert|6|mi|km}} wide from north to south, and up to {{convert|120|ft|m}} deep.<ref name="Frierson, pp. 4–5">Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 4–5.</ref>

===Allied plans===
[[File:Vice Admiral Kinkaid and General MacArthur on board USS Phoenix (CL-46), 28 February 1944 (SC 188839).jpg|thumb|right|Vice Admiral [[Thomas C. Kinkaid]] (left centre) with General [[Douglas MacArthur]] (centre) on the flag bridge of {{USS|Phoenix|CL-46|6}} during the pre-invasion bombardment of [[Los Negros Island]].|alt=Sailors wearing steel helmets stand by an anti-aircraft gun on a quadruple mount. Two officers lean on the railing, staring off into the distance.]]
In July 1942, the [[Joint Chiefs of Staff]] approved a series of operations against the Japanese bastion at Rabaul, which blocked any Allied advance along the northern coast of [[New Guinea]] towards the [[Philippines]] or northward towards the main Japanese naval base at [[Chuuk Lagoon|Truk]]. In keeping with the overall Allied [[grand strategy]] of [[Europe first]], the immediate aim of these operations was not the defeat of Japan but merely the reduction of the threat posed by Japanese aircraft and warships based at Rabaul to air and sea communications between the United States and Australia. By agreement among the Allied nations, in March 1942 the [[Asiatic-Pacific Theater|Pacific theatre]] was divided into the [[South West Pacific Area (command)|South West Pacific Area]], under General Douglas MacArthur, and the [[Pacific Ocean Areas (command)|Pacific Ocean Areas]], under [[Admiral (United States)|Admiral]] [[Chester W. Nimitz]]. Rabaul fell within MacArthur's area but the initial operations in the southern [[Solomon Islands]] came under Nimitz.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', pp. 1–2.</ref> The Japanese reaction was more violent than anticipated and some months passed before the [[Guadalcanal Campaign]] was brought to a successful conclusion. Meanwhile, General MacArthur's forces—primarily Australian—fought off a series of Japanese offensives in [[Territory of Papua|Papua]] in the [[Kokoda Track Campaign]], [[Battle of Milne Bay]], [[Battle of Buna-Gona]], and the [[Battle of Wau]].<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', pp. 5–6.</ref>

At the Pacific Military Conference in March 1943, the Joint Chiefs of Staff approved the latest version of General MacArthur's Elkton plan for an advance on Rabaul. Owing to a shortage of resources, particularly [[heavy bomber]] aircraft, the final stage of the plan, the capture of Rabaul itself, was postponed until 1944.<ref>Hayes, ''The History of the Joint Chiefs of Staff in World War II: The War Against Japan'', pp. 312–334.</ref> By July 1943, the Joint Chiefs were considering the possibility of neutralising and bypassing Rabaul, but the navy would still need a forward fleet base.<ref>Hayes, ''The History of the Joint Chiefs of Staff in World War II: The War Against Japan'', pp. 425–430.</ref> The Admiralty Islands, already a part of the Elkton plan, could serve this purpose, as they contained flat areas for airstrips, space for military installations, and Seeadler Harbour, which was large enough to accommodate a naval task force.<ref name="Morison, p. 432">Morison, ''Breaking the Bismarcks Barrier'', p. 432.</ref> On 6 August 1943, the Joint Chiefs of Staff adopted a plan that called for the neutralisation rather than the capture of Rabaul, and scheduled the invasion of the Admiralty Islands for 1 June 1944.<ref>Hayes, ''The History of the Joint Chiefs of Staff in World War II: The War Against Japan'', pp. 427–430.</ref>

{{quote box
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'''Task Force Brewer Assault Echelon Units'''<ref name="Krueger">Krueger, Walter, ''Report on Brewer Operation'', 2 August 1944, AWM54 519/1/12</ref>
<br />Brigadier General William C. Chase
* 2nd Squadron, 5th Cavalry Regiment
* Battery B, 99th Field Artillery Battalion
* 673rd Anti-Aircraft Machine Gun Battery (Airborne)
* Reconnaissance Platoon, HQ Troop, 1st Cavalry Brigade
* Communications Platoon, HQ Troop, 1st Cavalry Brigade
* 1st Platoon, Troop B (Clearing), 1st Medical Squadron
* 30th Portable Surgical Hospital
* ANGAU Detachment
* Air Force Detachment
* Naval Gunfire Support Party
* Air Liaison Party
}}

Throughout January 1944, [[AirSols]] aircraft based in the [[Solomon Islands (archipelago)|Solomon Islands]] and [[Royal Australian Air Force]] (RAAF) aircraft based on [[Kiriwina]] kept up a sustained air offensive against Rabaul. Under steady and relentless pressure, the Japanese air defence began to weaken, allowing a landing to be made on 15 February by New Zealand troops on the [[Battle of the Green Islands|Green Islands]], which lie little more than {{convert|100|mi|km}} from Rabaul. On 16 and 17 February, the [[US Pacific Fleet]]'s [[Task Force 58]] [[Operation Hailstone|attacked the main Japanese base at Truk]]. Most Japanese aircraft were recalled to defend Truk and 19 February saw the last significant interception of Allied aircraft over Rabaul.<ref>Mortensen, "Rabaul and Cape Gloucester", in Craven and Cate (eds), ''Guadalcanal to Saipan'', pp. 350–356.</ref> Meanwhile, on 13 February General MacArthur, who received an intelligence windfall from the [[Japanese army and diplomatic codes#Find of Japanese Army records|capture of Japanese Army code books]] by his Australian soldiers at [[Battle of Sio|Sio]], had issued orders for the invasion of the Admiralty Islands, codenamed Operation Brewer, which was now scheduled for 1 April. Forces assigned included the 1st Cavalry Division; [[No. 73 Wing RAAF]], providing [[close air support]]; the 592nd Engineer Boat and Shore Regiment (EBSR); the [[United States Marine Corps|US Marines]]' 1st Amphibious Tractor Battalion; and US [[Seabee (US Navy)|Naval Construction Battalions]] ("Seabees") to build the naval base—a total of 45,000&nbsp;personnel.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', pp. 316–317. Due to changes in plans, not all of the assigned units would actually be deployed.</ref> However, on 23 February 1944 three [[Fifth Air Force]] [[B-25 Mitchell]] bombers flew low over Los Negros. The airmen reported that there were no signs of enemy activity and the islands had been evacuated.<ref>''Reports of General MacArthur'', Volume I, p. 137.</ref> [[Lieutenant General]] [[George Kenney]], the commander of Allied Air Forces in the South West Pacific Area, went to MacArthur and proposed that the unoccupied islands be quickly taken by a small force. According to Kenney: "The General listened for a while, paced back and forth as I kept talking, nodded occasionally, then suddenly stopped and said: That will put the cork in the bottle."<ref>Kenney, ''General Kenney Reports'', p. 360.</ref>

Orders went out on 24 February 1944 for a reinforced squadron of the 1st Cavalry Division to carry out a reconnaissance in force in just five days time. If the Admiralty Islands were indeed evacuated, they would be occupied and a base developed. If the enemy was unexpectedly strong, then the force could be withdrawn. General MacArthur and [[Vice Admiral]] [[Thomas C. Kinkaid]], the commander of Allied Naval Forces in the South West Pacific Area, would be on hand to make the decision but otherwise they delegated command to [[Rear Admiral]] [[William Fechteler]], the commander of Amphibious Group&nbsp;8 of Rear Admiral [[Daniel E. Barbey]]'s [[VII Amphibious Force]]. To accommodate them, the [[light cruiser]] {{USS|Phoenix|CL-46|6}} was ordered to sea. At the time, she was in [[Brisbane]], with over 300&nbsp;of her crew on shore leave. Trucks with [[bull horn]]s broadcast the code word recalling the crew.<ref>Morison, ''Breaking the Bismarcks Barrier'', p. 435.</ref> To achieve surprise, and to reach the Admiralty Islands in just five days, [[high speed transport]]s (APDs) were required; [[Landing Ship, Tank|Landing Ships, Tank]] (LSTs) were too slow to make the required distance in the time.<ref>Barbey, ''MacArthur's Amphibious Navy'', pp. 145–151.</ref> Only three APDs were available: {{USS|Brooks|DD-232|6}}, {{USS|Humphreys|DD-236|2}} and {{USS|Sands|DD-243|2}}. Each could accommodate 170&nbsp;men. The remaining troops were carried on nine [[destroyer]]s: {{USS|Bush|DD-529|6}}, {{USS|Drayton|DD-366|2}}, {{USS|Flusser|DD-368|2}}, {{USS|Mahan|DD-364|2}}, {{USS|Reid|DD-369|2}}, {{USS|Smith|DD-378|2}}, {{USS|Stevenson|DD-645|2}}, {{USS|Stockton|DD-646|2}} and {{USS|Welles|DD-628|2}}. Between them, the destroyers and APDs carried 1,026 troops.<ref>Morison, ''Breaking the Bismarcks Barrier'', pp. 436–437.</ref>

{{quote box
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'''Task Force Brewer Supporting Echelon Units'''<ref name="Krueger"/>
<br />Colonel Hugh Hoffman
* 5th Cavalry Regiment (less 2nd Squadron)
* 99th Field Artillery Battalion (less Battery B)
* 1st Platoon, Troop A, 8th Engineer Squadron
* 1st Collecting Troop, 1st Medical Squadron
* Signal Detachment, 1st Signal Troop
* 40th Naval Construction Battalion
* Battery C, 168th Anti-Aircraft Artillery Battalion (Gun)
* Battery A, 211th Coast Artillery Battalion (Anti-Aircraft) (Automatic Weapons)
* Company E, Shore Battalion, 592nd Engineer Boat and Shore Regiment
}}

This force was commanded by [[Brigadier General]] William C. Chase, commander of the 1st Brigade, 1st Cavalry Division.<ref>Hirrel, ''Bismarck Archipelago'', p. 14.</ref> It included the three rifle troops and the heavy weapons troop of the 2nd&nbsp;Squadron, [[5th Cavalry Regiment (United States)|5th Cavalry]]; a platoon from Battery&nbsp;B, 99th&nbsp;Field Artillery Battalion with two [[M116 howitzer|75 mm pack howitzers]]; the 673rd Anti-Aircraft Machine Gun Battery (Airborne);<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 18–19.</ref> and 29&nbsp;Australians of the [[Australian New Guinea Administrative Unit]] (ANGAU), who were to assist in gathering intelligence and dealing with the native population, some 13,000 of whom lived in the islands.<ref>Powell, ''The Third Force:ANGAU's New Guinea War 1942–46'', p. 82.</ref> Once the decision to remain was known, a follow-up force with the rest of the 5th Cavalry and 99th Field Artillery Battalion, 40th Naval Construction Battalion, and 2,500&nbsp;measurement [[ton]]s of stores would depart from Finschhafen in six [[Landing Ship, Tank|Landing Ships, Tank]] (LSTs), each towing an [[Landing Craft Mechanized|LCM]] of Company&nbsp;E, 592nd&nbsp;EBSR.<ref>Barbey, ''MacArthur's Amphibious Navy'', p. 152.</ref> When an aide expressed concern over assigning such a hazardous mission to a unit without combat experience, General MacArthur recalled how the 5th&nbsp;Cavalry had fought alongside his [[Arthur MacArthur, Jr.|father]]'s troops in the campaign against [[Geronimo]]. "They'd fight then," he said, "and they'll fight now."<ref>Taafe, ''MacArthur's Jungle War'', p. 61.</ref>

[[Major General]] [[Charles A. Willoughby]]'s G-2 ([[Military intelligence|intelligence]]) section did not agree with the airmen's assessment the islands were unoccupied. Drawing on [[Ultra (cryptography)|Ultra]] and [[Allied Intelligence Bureau]] reports from interrogating local civilians, it reported on 15 February that there were 3,000&nbsp;Japanese troops in the Admiralty Islands. On 24 February, it revised the estimate to 4,000. G-2 attributed the lack of anti-aircraft fire to the Japanese logistical situation, believing it was a measure to conserve ammunition.<ref>''Reports of General MacArthur'', Volume I, pp. 137–138.</ref> Lieutenant General [[Walter Krueger]], the commander of [[Sixth United States Army|US Sixth Army]] later recalled no one at his headquarters believed the islands unoccupied. In the original plan, a team of [[Alamo Scouts]] was to have thoroughly reconnoitred the island before the landing. Krueger had a six-man party of Alamo Scouts inserted on the southern coast of Los Negros by [[PBY Catalina|PBY]] under cover of a bombing raid on 27 February. The scouts reported the south coast was "lousy with Japs".<ref>Krueger, ''From Down Under to Nippon'', pp. 48–49.</ref>

===Japanese defences===
The Japanese defence of the Admiralties fell under the [[Japanese Eighth Area Army|Eighth Area Army]], based at Rabaul and commanded by General [[Hitoshi Imamura]]. In September 1943, as a result of the failure to stop Allied advances in New Guinea and the [[Solomon Islands Campaign|Solomons]], the [[Imperial General Headquarters]] (IGHQ) had decided to constrict Japan's defensive perimeter in the south and central Pacific to a new line stretching from the [[Banda Sea]] to the [[Caroline Islands]]. The IGHQ charged Imamura with holding his portion of the new line, which included the Admiralties, as long as possible to allow the Japanese navy and army time to prepare "decisive" counterattacks against Allied forces. Maintaining control of the Admiralties was crucial to the Japanese defensive plans, as possession of the islands by the Allies would place the key Japanese stronghold at [[Chuuk State|Truk]] within range of heavy bombers. Apparently not expecting the Allies to move on the Admiralties so quickly, IGHQ gave Imamura until the middle of 1944 to complete the defensive preparations for his command.<ref>Hayashi, '' Kogun: The Japanese Army in the Pacific War'', pp. 72–73.</ref> At this time the largest Japanese unit in the islands was the 51st Transport Regiment, which had arrived on Los Negros in April.<ref name="Drea_99">Drea, '' MacArthur's Ultra'', p. 99</ref>

Imamura sought reinforcements for the Admiralties in late 1943 and early 1944. In October 1943 he requested an infantry division for the islands, but none was available. A subsequent proposal to transfer the 66th Regiment from the Palaus, where it was being rebuilt after suffering heavy losses, to the Admiralties was also unsuccessful as IGHQ believed that the [[Eighteenth Army (Japan)|Eighteenth Army]] had greater need for this unit. The [[Imperial Japanese Navy]] (IJN) also rejected Imamura's suggestion that a [[Japanese Special Naval Landing Forces|special naval landing force]] unit be dispatched to the islands.<ref name="Drea_99" /> IGHQ agreed to deploy the 66th Regiment to the Admiralties in January 1944 to bolster the region's defences following the Allied landings at [[Battle of Arawe|Arawe]] and [[Landing at Saidor|Saidor]] in mid-December and early January respectively, but this movement was cancelled after a ship carrying reinforcements for the regiment was sunk by {{USS|Whale|SS-239|6}} with heavy loss of life on the 16th of the month.<ref>Drea, '' MacArthur's Ultra'', p. 100</ref> Following this disaster Imamura directed the [[38th Division (Imperial Japanese Army)|38th Division]] to dispatch a battalion to the islands, and 750 men of the 2nd&nbsp;Battalion, 1st Independent Mixed Regiment arrived there on the night of 24/25 January. A subsequent attempt to ship an infantry and an artillery battalion to the Admiralties was frustrated by Allied air and submarine attacks, but 530 soldiers of the 38th Division's 1st&nbsp;Battalion, [[229th Infantry Regiment (Imperial Japanese Army)|229th Infantry Regiment]] arrived there on the night of 2 February. Most of these troop movements were detected by Allied intelligence.<ref>Drea, '' MacArthur's Ultra'', p. 101</ref>

At the time of the Allied landing, [[Imperial Japanese Army]] forces in the Admiralties consisted of the 51st Transport Regiment under Colonel Yoshio Ezaki, who was also the overall garrison commander; 2nd&nbsp;Battalion, 1st Independent Mixed Regiment; 1st&nbsp;Battalion, 229th Infantry Regiment; and elements of the IJN's 14th Naval Base Force.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', p. 319.</ref><ref>Jersey, ''Hell's Islands'', pp. 360–361, 366–367. The 1st&nbsp;Battalion, 229th&nbsp;Infantry Regiment, consisting mainly of soldiers from [[Gifu Prefecture]], Japan, had served on Guadalcanal beginning in November 1942 before [[Operation Ke|being evacuated]] to Rabaul in February 1943. On Guadalcanal, the battalion was commanded by Major Tsuguto Tomoda but it is not clear whether he was still with the battalion in the Admiralties.</ref> Allied G-2 had identified the presence of all these units in the Admiralties, though their designation was not known in all instances. While the 1st&nbsp;Battalion, 229th&nbsp;Infantry Regiment was a veteran of several campaigns, it was short of equipment and lacked its battalion artillery guns. The 2nd&nbsp;Battalion, 1st Independent Mixed Regiment was led by reserve officers who had seen action in China, but most of its enlisted men were recalled reservists who had not previously been in battle.<ref>Drea, '' MacArthur's Ultra'', pp. 102–103</ref>

The 51st Transport Regiment had constructed an airstrip on Lorengau and commenced another, known as [[Momote Airport|Momote Airstrip]], at the Momote Plantation on Los Negros. Lorengau was used as a staging point for aircraft moving between Rabaul and airstrips in North East New Guinea. The importance of the Admiralty Islands to the Japanese increased as the result of Allied advances in New Guinea and [[New Britain]] which blocked off other air routes.<ref>''Reports of General MacArthur'', Volume II, part I, pp. 244–245.</ref> By February, both airstrips were unserviceable and the antiaircraft guns were silent to conserve ammunition and conceal their positions. Ezaki had ordered his men to neither move nor fire in daylight.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', p. 320.</ref>

==Battle of Los Negros==

===Landing===
[[File:WW2 Admiralty Islands ops.jpg|thumb|Admiralty Islands operations, 29 February&nbsp;– 30 May 1944|alt=Topographic map of the islands surrounding Seeadler Harbour. There are four small islands to the north, while the much larger Los Negros is to the east and southeast and Manus lies to the southwest.]]
The chosen landing site was a small beach on the south shore of Hyane Harbour near the Momote airstrip. The airstrip could be seized quickly; but the surrounding area was [[mangrove]] swamp, and the harbour entrance was only about {{convert|750|yd|m|-2}} wide. "Since the whole operation was a gamble anyway," [[Samuel Eliot Morison]] noted, "one might as well be consistent."<ref>Morison, ''Breaking the Bismarcks Barrier'', p. 436.</ref> The gamble paid off. The Japanese had not anticipated a landing at this point and the bulk of their forces were concentrated to defend the beaches of [[Seeadler Harbour]], on the other side of the island.<ref>Hirrel, ''Bismarck Archipelago'', pp. 14–15.</ref> The weather on 29 February 1944 was overcast with a low cloud ceiling that prevented most of the planned air strike. Only three [[B-24 Liberator|B-24s]] and nine B-25s found the target. The naval bombardment was therefore extended for another 15&nbsp;minutes.<ref name=f23>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 23.</ref> Each APD lowered four [[Landing craft|LCPRs]] (Landing Craft, Personnel, Ramped). Each LCPR carried its maximum load of 37&nbsp;men, who boarded by climbing over the APDs' sides and down cargo nets.<ref name=f23/> The unarmoured LCPRs were still used because [[davit]]s had not been strengthened to carry the heavier, armoured [[LCVP (United States)|LCVP]] (Landing Craft, Vehicle, Personnel).<ref>Friedman, ''US Amphibious ships and craft'', p. 207.</ref>

[[File:MacArthur and Henshaw.jpg|thumb|left|Admiralty Islands, 29 February 1944. General Douglas MacArthur decorates the first man ashore, 2nd Lieutenant Marvin J. Henshaw, with the [[Distinguished Service Cross (United States)|Distinguished Service Cross]]|alt=Officer in raincoat shakes hand of soldier wearing steel helmet and waterproof poncho while other similarly attired soldiers look on.]]
The first wave landed without casualties at 08:17, but once the bombardment lifted the Japanese emerged from their dugouts and machine guns and shore batteries began firing. The landing craft, on returning, came under [[crossfire]] from enemy machine guns on both sides of the harbour. The fire became so heavy the second wave was forced to reverse course until the enemy fire was suppressed by destroyers. The third and fourth waves also came under fire.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 23–27.</ref> A correspondent from ''[[Yank, the Army Weekly]]'' described the scene:
{{blockquote|text=As we neared the channel, the Navy men in the bow hollered to us to keep our heads down or we'd get them blown off. We crouched lower, swearing, and waited. It came with a crack; machine-gun fire over our heads. Our light landing craft shuddered as the Navy gunners hammered back and answered with the [[M1919 Browning machine gun|.30&nbsp;calibers]] mounted on both sides of the barge. As we made the turn for the beach, something solid plugged into us. "They got one of our guns or something," one GI said. There was a splinter the size of a half-dollar on the pack of the man in front of me. Up front a hole gaped in the middle of the landing ramp and there were no men where there had been four. Our barge headed back toward the destroyer that had carried us to the Admiralties. White splashes of water were plunging through the six-inch gap in the wooden gate. William Siebieda, [[Seaman (rank)|S 1/c]], of [[Wheeling, West Virginia]], ducked from his position at the starboard gun and slammed his hip against the hole to plug it. He was firing a tommy gun at the shore as fast as wounded soldiers could pass him loaded clips. The water sloshed around him, running down his legs and washing the blood of the wounded into a pink frappe.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 28.</ref> }}

Four of the twelve LCPRs had been damaged. Three were soon repaired, but they could not be risked further, for without them, the reconnaissance force could not be evacuated. The emergency plan provided for an APD to enter the harbour and take troops off from a jetty but this would clearly be a desperate measure indeed. Over the next four hours, the boats continued to make trips to the beach, but only when it was believed destroyers had suppressed enemy fire. Heavy rain made it safer by reducing visibility. The last destroyer was unloaded at 12:50. By this time, the navy had lost two men dead and three wounded.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 29.</ref>

For the moment it was safer ashore. The cavalrymen overran the airstrip. Sporadic opposition allowed them to set up the antiaircraft machine guns on the beach, unload supplies, and patrol inland. Two soldiers were killed and three wounded. At 16:00, General MacArthur and Admiral Kinkaid came ashore. The general inspected the position.<ref name=f31/> A lieutenant warned him a Japanese sniper had been killed in the vicinity just a few minutes before. "That's the best thing to do with them," the General replied.<ref>Manchester, ''American Caesar'', p. 341.</ref> He decided to stay, ordering Chase to hold his position until the follow-up force arrived, then returned to ''Phoenix''. Fechteler's force departed at 17:29, the transports having unloaded and most of the bombardment force having exhausted its ammunition. ''Bush'' and ''Stockton'' remained to provide on-call naval fire support.<ref name=f31>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 31.</ref>

===Battle for the beachhead===
[[File:Admiralties-day01.JPG|thumb|Situation on Los Negros on the night of 29 February 1944|alt=Map showing a tiny perimeter nestled next to an airstrip.]]

Chase pulled his troops back into a tight perimeter. There was no barbed wire, so the whole area had to be covered. The ground was hard [[coral]], which was good for airbase construction but made it difficult to dig foxholes. The twelve .50&nbsp;calibre (12.7mm) machine guns were positioned in the front line.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 31–32.</ref> There was fighting throughout the night as small groups of Japanese attempted to infiltrate the position.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 35.</ref> An airdrop of ammunition was requested. A break in the weather allowed three B-25s of the 38th US Bomb Group to drop supplies at 08:30. Four B-17s of the [[375th Airlift Wing|375th Troop Carrier Group]] each dropped three tons of supplies, including blood plasma, ammunition, hand grenades, and barbed wire.<ref>Futrell and Mortensen, "The Admiralties", in Craven and Cate (eds), ''Guadalcanal to Saipan'', p. 565.</ref> Some of the ammunition fell beyond the perimeter but for some reason men who moved out to retrieve it were not fired upon.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 36.</ref>

The Japanese were not expected to make another effort until dark but at around 16:00 a Japanese patrol was discovered that had somehow managed to infiltrate the perimeter in broad daylight and penetrate to within {{convert|35|yd|m|abbr=on}} of Chase's command post. A sniper fired on the command post, and fire was directed at the patrol. Major [[Julio Chiaramonte]], [[Staff officer|S-2]] (intelligence officer) of the task force, set out with four men to silence the sniper. As his party closed in, there were a series of explosions. Three Japanese had committed suicide with hand grenades, while another had committed ''[[seppuku]]'' with his sword. Fifteen dead officers and sergeants were counted, including Captain Baba, the commander of the Japanese battalion which made the attack the preceding night. The Japanese launched another attack on the perimeter at 17:00 but could make little progress in the face of American firepower.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 37–38.</ref>

[[File:Admiralties-day03.JPG|thumb|Situation on Los Negros on the night of 2 March 1944|alt=Map showing an expanded perimeter that now includes the airstrip.]]
The next morning saw the arrival of the follow-up force, six LSTs, each towing an LCM, escorted by the destroyers {{USS|Mullany|DD-528|6}} and {{USS|Ammen|DD-527|2}} and {{HMAS|Warramunga|I44|6}} and [[destroyer minesweeper]]s {{USS|Hamilton|DD-141|6}} and {{USS|Long|DD-209|2}}. The LSTs entered Hyane Harbour and beached, coming under mortar fire as they did so. {{USS|LST-202||2}}, crewed by the [[United States Coast Guard]], replied with [[3"/50 caliber gun|3 in]] (76&nbsp;mm) and [[Bofors 40 mm Automatic Gun L/60|Bofors 40 mm gun]]s.<ref>Morison, ''Breaking the Bismarcks Barrier'', p. 440.</ref> The LSTs were unloaded over the next seven hours. In the process, ammunition, construction equipment, and stores piled up. To accommodate a proper dispersal of stores, Chase ordered an attack to expand the perimeter.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 39, 42.</ref> An air strike was requested. B-25s of the 345th US Bomb Group were intercepted by an estimated fifteen Japanese fighters. These were driven off by eight escorting [[P-47 Thunderbolt]] fighters, which claimed eight Japanese aircraft shot down. Two [[B-17 Flying Fortress|B-17s]] of the 69th&nbsp;US Troop Carrier Squadron on a supply dropping run were also attacked, and claimed to have shot one of their attackers down. Two of the four B-25 squadrons dropped bombs in areas occupied by American troops, two of whom were killed and four wounded before the 12th US Air Liaison Party could correct the error.<ref>Futrell and Mortensen, "The Admiralties", in Craven and Cate (eds), ''Guadalcanal to Saipan'', p. 566.</ref> Both squadrons of the 5th Cavalry attacked at 15:00. All objectives were taken and a new, larger defensive perimeter was prepared.<ref name=f3941>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 39–41.</ref> The 40th Naval Construction Battalion had landed expecting to work on Momote airstrip. Instead, they were ordered to use their equipment to clear fields of fire and construct fortifications, and were given a section of the perimeter to defend.<ref>Barbey, ''MacArthur's Amphibious Navy'', p. 156.</ref> Six trenches were dug out by a bulldozer and ten men stationed in each. Their [[Excavator|ditch digger]] scooped out a {{convert|300|yd|m|adj=on}} trench which formed a secondary line of defence. The airstrip's revetments were transformed into heavy machine gun posts.<ref name=f3941/>

The two destroyer minesweepers were supposed to sweep the entrance to [[Seeadler Harbour]] between Hauwei and Ndrilo Islands but fire from at least one Japanese {{convert|4|in|mm|adj=on|0}} gun on Hauwei Island prevented them from entering the harbour. Captain [[Emile Dechaineux]], commanding the destroyers supporting the forces ashore, brought ''Ammen'', ''Bush'', ''Mullany'' and ''Warramunga'' around and bombarded the island. The Japanese guns ceased fire but came alive again when another attempt was made to sweep the channel. Dechaineux then called off the effort, ordering the DMSs to join him. The destroyers bombarded Japanese guns covering the entrance to Hyane Harbour to allow the LSTs to leave unmolested.<ref name=g374>Gill, ''Royal Australian Navy 1942–1945'', p. 374.</ref> One LST left with between 20 and 30&nbsp;truckloads of stores still aboard. The LSTs did not wish to remain after dark as a Japanese attack was expected.<ref>Casey, ''Amphibian Engineer Operations'', p. 232.</ref> Dechaineux escorted them part of the way until he received an order from Admiral Barbey for ''Ammen'', ''Mullany'', ''Warramunga'', and ''Welles'' to remain off Los Negros. ''Ammen'' and ''Mullany'' bombarded Hauwei Island again in the morning, setting off a couple of ammunition dumps, but still came under accurate fire from four or five guns, and Dechaineux was forced to inform Barbey that he was unable to overcome the island's guns.<ref name=g374/>

Krueger was gravely concerned about the seriousness of the situation on Los Negros. In response to urgent request from Chase, Krueger arranged with Barbey for the movement of the rest of the 1st Cavalry Division to be expedited. At Krueger's request, the 2nd&nbsp;Squadron, [[7th Cavalry Regiment (United States)|7th Cavalry]] would travel in the three APDs. Other units would arrive on 6 and 9 March instead of 9 and 16 March. Krueger realised that Hyane harbour was too small to support the entire division, but there were good beaches around Salami Plantation on the western shore of Los Negros. To use them, and to permit a shore-to-shore operation against Manus from Los Negros, Seeadler Harbour would have to be opened up.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', p. 336.</ref>

From the Japanese perspective, the battle was not going too well either. The Japanese had expected a landing on Seeadler Harbour, this being the logical American objective, and had concentrated their forces around the Lorengau airfield. The defence of the Momote airstrip and Hyane harbour was the responsibility of Baba Force, built around Captain Baba's 1st&nbsp;Battalion, 229th Infantry Regiment. Colonel Ezaki ordered Baba to attack the beachhead but a suspicion the Hyane Harbour landing was a diversion, coupled with false reports of enemy activity at Salami had him retain the 2nd (Iwakami) Battalion of the 1st Independent Infantry Regiment there instead of sending it to assist Baba Force. By 2 March, Ezaki had resolved to attack the Hyane beachhead with his whole force. The difficulties imposed by the terrain, and disruption by American artillery and Allied naval gunfire, forced a postponement of the attack to the night of 3 March.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 52–57.</ref>

At 21:00, a lone Japanese plane dropped eight bombs, cutting telephone wires. Once it had departed, yellow flares went up and a Japanese infantry attack was launched, supported by mortar fire.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 45.</ref> Offshore, Dechaineux' destroyers came under attack from four [[Mitsubishi G4M|''Betty'']] bombers.<ref>Gill, ''Royal Australian Navy 1942–1945'', p. 375.</ref> 1st Squadron, 5th Cavalry, was attacked by about two reinforced platoons, which were met by heavy automatic weapons and mortar fire. The heavy jungle in this sector permitted some infiltration but the Japanese force was not strong enough to overrun the position.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 45–46.</ref> The main Japanese attack was delivered by 2nd Battalion, 1st Independent Mixed Regiment, from the direction of the native skidway, together with detachments from the Porlaka area, and fell on 2nd&nbsp;Squadron, 5th&nbsp;Cavalry. The troopers noticed a change in Japanese tactics. Instead of infiltrating silently, they advanced across the open, talking and in some cases singing. Their advance took them straight into anti-personnel mines and booby traps, which duly exploded, and then into the fields of fire of the Americans' automatic weapons, including several .30 [[M1917 Browning machine gun|water-cooled Browning]] machineguns, but the advance continued.<ref name="dunlap">Dunlap, Roy F., ''Ordnance Went Up Front'', p. 310.</ref> The guns of the 211th Coast Artillery (AA) Battalion and 99th Field Artillery Battalion fired through the night, attempting to break up the Japanese attack from Porlaka. Shortly after midnight, Japanese barges attempted to cross Hyane harbour but were engaged by anti-aircraft guns and did not reach the American positions. A Bofors 40&nbsp;mm gun position was captured by the Japanese, who in turn were driven off by the Seabees.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 46–49.</ref> Manning the .30s, the 5th&nbsp;Cavalry's gunners piled up the Japanese dead until the guns had to be moved to get clear fields of fire. One of the Browning guns that held the position was later left in its place, as a monument.<ref name="dunlap" /> Sergeant [[Troy McGill]] occupied a revetment with his squad of eight men. All were killed or wounded except McGill and another man, whom he ordered to fall back to the next revetment. McGill fired his rifle until it jammed, then clubbed the Japanese with it until he was killed. He was posthumously awarded the [[Medal of Honor]].<ref>{{cite web| url= https://www.army.mil/medalofhonor/citations22.html | title = World War II Medal of Honor Citations| publisher = United States Army Center of Military History |access-date=3 July 2021 }} McGill's citation referred to the Japanese as "drinkcrazed" but postmortems indicated this was not the case.</ref>

By dawn, the Japanese attack had subsided. Over 750&nbsp;Japanese dead were counted in and around the American positions. No prisoners were taken. American casualties were 61&nbsp;dead, and 244&nbsp;wounded, including nine dead and 38&nbsp;wounded Seabees.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 50.</ref> The 2nd&nbsp;Squadron, 5th&nbsp;Cavalry and the 40th Naval Construction Battalion received [[Presidential Unit Citation (United States)|Presidential Unit Citations]].<ref name="brewer">Krueger, Walter, ''Report on Brewer Operation'', 2 August 1944, AWM54 519/1/12.</ref> General Chase called for an airdrop of ammunition, prodigious quantities of which had been expended during the night, and had ''Warramunga'' fire on the native skidway.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 50–51.</ref>

===Securing Seeadler Harbour===
[[File:Admiralties-day08.JPG|thumb|Operations on Los Negros, 5–7 March 1944|alt=Larger scale map shows all of Los Negros.]]
The morning of 4 March saw the arrival of the 2nd&nbsp;Squadron, 7th&nbsp;Cavalry, which relieved the 2nd&nbsp;Squadron, 5th&nbsp;Cavalry. The next day Major General [[Innis P. Swift]], the commander of the 1st Cavalry Division, arrived aboard ''Bush'' and assumed command. He ordered the 2nd&nbsp;Squadron, 7th&nbsp;Cavalry to attack across the native skidway. The 2nd&nbsp;Squadron, 5th&nbsp;Cavalry therefore went back into the line to relieve them. While the relief was taking place, the Japanese launched a daylight attack. This was repulsed by the cavalrymen, with the help of artillery and mortar fire, but the American attack was delayed until late afternoon. It then ran into a Japanese minefield and by dawn the advance had only reached as far as the skidway.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 58–60.</ref>

On the morning of 6 March, another convoy arrived at Hyane Harbour: five LSTs, each towing an LCM, with the [[12th Cavalry Regiment (United States)|12th Cavalry]] and other units and equipment including five [[Landing Vehicle Tracked|Landing Vehicles Tracked]] (LVTs) of the 592nd&nbsp;EBSR, three [[M3 Stuart|M3 light tanks]] of the 603rd Tank Company, and twelve [[M101 howitzer|105mm howitzers]] of the 271st Field Artillery Battalion.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', p. 338.</ref> The 12th&nbsp;Cavalry was ordered to follow the 2nd&nbsp;Squadron, 7th&nbsp;Cavalry in its advance to the north, and to capture the Salami Plantation. The road to Salami was little more than a muddy track in which vehicles soon became bogged. The Japanese also obstructed the route with ditches, felled trees, snipers, and booby traps.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 61–63.</ref> [[Warrant Officer|WO2]] R.&nbsp;J. Booker of ANGAU used his local knowledge to guide the 12th Cavalry and the three tanks to Salami.<ref name="p84"/> Here the Japanese put up a fierce fight that lasted over an hour. The tanks fired [[canister shot]] shells into buildings and high-explosive shells into the slits of Japanese bunkers.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 63–64.</ref>

The inhabitants of the area informed the ANGAU detachment the Japanese had retreated across Seeadler Harbour to Papitalai Mission. This, therefore, became the next objective. The 5th&nbsp;Cavalry would attack Papitalai Plantation from the east while the 2nd&nbsp;Squadron, 12th&nbsp;Cavalry would attack Papitalai Mission. The 5th&nbsp;Cavalry captured Porlaka without opposition and crossed Lemondrol Creek in canvas and rubber boats.<ref>Casey, ''Amphibian Engineer Operations'', p. 238.</ref> A patrol under Captain William C. Cornelius fought an estimated 50&nbsp;Japanese, who ultimately withdrew. Cornelius, who was credited with killing four, was severely wounded and died the next day. He was posthumously awarded the Distinguished Service Cross.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 65.</ref>

[[File:Krueger Chase and Swift.jpg|thumb|left|Senior American commanders on Los Negros: Lieutenant General Walter Krueger,
Brigadier General William C. Chase and Major General Innis P. Swift|alt=Four officers in a jeep, with a steel helmeted driver. The one on the left is wearing a garrison cap with three stars, the one in the centre a cloth peaked cap with one star, while the one on the right had a steel helmet with two stars.]]

Because of the coral reef, conventional landing craft could not be used for the landing at Papitalai Mission. The five LVTs, one a combat type and the other four cargo-carrying, set out from Hyane Harbour to Salami Plantation but the road was so bad that only the combat and one cargo LVT were available in time. The attack went ahead anyway, preceded by an airstrike and artillery bombardment by the 271st Field Artillery Battalion. The combat LVT fired 24&nbsp;[[M8 (rocket)|M8 4.5-inch rockets]]. Return fire was received from Japanese mortars and machine guns, and a 75&nbsp;mm howitzer.<ref>Casey, ''Amphibian Engineer Operations'', pp. 236–237.</ref> The first wave had to hold alone in the face of fire from Japanese bunkers for 45&nbsp;minutes until the LVTs returned with the next wave. Later, they fought off a counterattack by about 30&nbsp;Japanese.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 66.</ref> Joined by a third LVT which had eventually managed to make it to Salami, the LVTs made 16&nbsp;trips across the harbour before nightfall curtailed operations, transporting part of the 2nd&nbsp;Squadron, 12th&nbsp;Cavalry, along with rations, water and ammunition, and evacuating the dead and wounded.<ref name=c237>Casey, ''Amphibian Engineer Operations'', p. 237.</ref>

Colonel Ezaki reported the American attack on Papitalai Mission to the Eighth Area Army in Rabaul, promising a night counterattack on the position; but no attack was delivered. The Japanese withdrew, and no further messages were ever received from Ezaki.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 67.</ref>

The task of silencing the Japanese guns guarding Seeadler Harbour fell to Rear Admiral [[Victor Crutchley]]'s Task Force&nbsp;74 (TF74), consisting of the [[heavy cruiser]] {{HMAS|Shropshire|73|6}}, light cruisers {{USS|Phoenix|CL-46|6}} and {{USS|Nashville|CL-43|2}}, and destroyers {{USS|Bache|DD-470|6}}, {{USS|Beale|DD-471|2}}, {{USS|Daly|DD-519|2}}, and {{USS|Hutchins|DD-476|2}}. They bombarded Hauwei Island for an hour on 4 March but on 6 March {{USS|Nicholson|DD-442|6}} was struck by a Japanese shell fired from Hauwei. With minesweepers scheduled to attempt to enter Seeadler Harbour again on 8 March, Admiral Kinkaid ordered Crutchley to try again. On the afternoon of 7 March, TF74 bombarded Hauwei, Ndrilo, Koruniat, Pityilu and northern Los Negros. ''Shropshire'' fired 64&nbsp;{{convert|8|in|mm|adj=on|0}} and 92&nbsp;{{convert|4|in|mm|adj=on|0}} shells, while the American cruisers and destroyers expended 1,144&nbsp;{{convert|5|in|mm|adj=on|0}} and {{convert|6|in|mm|adj=on|0}} shells.<ref>Gill, ''Royal Australian Navy 1942–1945'', pp. 375–377.</ref> The next day, two destroyers, two minesweepers, an LCM (flak) and six LCMs carrying trucks and supplies entered the Seeadler Harbour without being fired upon.<ref name="c237"/> This cleared the way for the 2nd&nbsp;Brigade, 1st&nbsp;Cavalry Division to land at Salmi on 9 March.

[[File:Kittyhawk on Momote.jpg|thumb|right|RAAF Kittyhawks on Momote Airstrip, 8 March 1944|alt=Two propeller aircraft parked on a crushed coral surface. In the background is a coconut plantation]]
By 7 March, the Seabees had the Momote airfield ready. Artillery spotting aircraft began operating from the strip on 6 March and a B-25 made an emergency landing the next day.<ref>Futrell and Mortensen, "The Admiralties", in Craven and Cate (eds), ''Guadalcanal to Saipan'', p. 568.</ref> Guided by a B-25, twelve [[Curtiss P-40|P-40 Kittyhawks]] of [[No. 76 Squadron RAAF]] arrived from Kiriwina via Finschhafen on 9 March, the remaining twelve aircraft of the squadron following the next day. They were joined by the ground crew of [[No. 77 Squadron RAAF]], which had arrived by LST on 6 March. The rest of No.&nbsp;73 Wing RAAF arrived over the next two weeks, including the Kittyhawks of No.&nbsp;77 Squadron RAAF and [[Supermarine Spitfire]]s of [[No. 79 Squadron RAAF]]. Operations began on 10 March and henceforth ships and ground units in the Admiralties had air support just minutes away.<ref>Odgers, ''Air War Against Japan'', pp. 175–177.</ref>

The ANGAU Detachment reached the town of Mokerang on 9 March and found fifty inhabitants. The Detachment was relieved to find islanders had not been deliberately ill-treated by the Japanese. The retreating Japanese had stripped their gardens of food, leaving the civilian population hungry, so ANGAU arranged for them to be provisioned by the Americans.<ref name=p84>Powell, ''The Third Force'', p. 84.</ref>

==Battle of Manus==

===Hauwei===
Operations on Los Negros had now reached the mopping-up stage, but an estimated 2,700&nbsp;Japanese troops remained on Manus. General Swift decided to land Brigadier General Verne D. Mudge's 2nd&nbsp;Brigade at Lugos Mission, west of Lorengau. Lorengau, known to be heavily fortified, was an important objective. It had an airfield, and four roads converged there. As a preliminary, the 302nd Cavalry Reconnaissance Troop was ordered to locate sites from which the artillery could cover landings on Manus.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 76–79.</ref> Three patrols were sent out by LCVP on 11 March. The first found Bear Point on Manus free of Japanese but lacking sites for artillery emplacements. The second scouted the Butjo Luo Islands. They found the islands apparently unoccupied, with good sites on the northern island. The third patrol, 25 officers and men of the 302nd Cavalry Reconnaissance Troop, two officers from the 99th Field Artillery Battalion,<ref name="Casey, p. 240">Casey, ''Amphibian Engineer Operations'', p. 240.</ref> with WO2 A.&nbsp;L. Robinson of ANGAU and Kaihu, a native of Mokerang, as guides, set out for Hauwei in an LCVP,<ref name="p84"/> escorted by PT 329,<ref>Bulkley, ''At Close Quarters'', p. 228.</ref> one of the [[PT boat]]s now operating from the [[Motor torpedo boat tender|tender]] {{USS|Oyster Bay|AGP-6|6}} in Seeadler Harbour.<ref>Morison, ''Breaking the Bismarcks Barrier'', p. 446.</ref>

As the patrol moved ashore, Major Carter S. Vaden spotted a well camouflaged [[bunker]] and threw two [[hand grenade]]s into it. When they exploded, concealed Japanese mortars and machine guns commenced firing on the patrol and the craft offshore. The PT was hit, her commander wounded, and she withdrew. The LCVP headed toward the shore where she picked up five men, including Robinson and Kaihu. The LCVP retracted and headed out to sea but then sighted another group on the beach. She headed back in to pick them up, despite her commander being wounded, and succeeded. As she backed off the beach again, she was holed by a mortar round and began taking on water. Meanwhile, the damaged PT had reported what had happened and a bomber was sent to investigate. Flying low, it spotted the men in the water, and another PT&nbsp;boat was sent to the rescue, covered by the destroyer {{HMAS|Arunta|I30|6}}. After three hours in the water, the LCVP's survivors were picked up by the PT boat. Eight Americans, including Vaden, had been killed and fifteen wounded, including the entire LCVP crew.<ref name=c2401>Casey, ''Amphibian Engineer Operations'', pp. 240–241.</ref> Kaihu was missing and Robinson was contemplating how he would break the news to his family when Kaihu walked in, having swum back to Los Negros.<ref name="powell">Powell, ''The Third Force'', p. 85.</ref>

General Swift postponed the landing on Lugos and ordered the 2nd Squadron, 7th Cavalry to capture Hauwei.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 80.</ref> Once again, Robinson acted as guide, notwithstanding severe sunburn from his time in the water the previous day.<ref name="powell" /> The landing was covered by the destroyers ''Arunta'', ''Bush'', ''Stockton'' and {{USS|Thorn|DD-647|2}};<ref name="Gill, p. 378">Gill, ''Royal Australian Navy 1942–1945'', p. 378.</ref> a pair of rocket-firing LCVPs and the LCM (flak), which fired 168&nbsp;{{convert|4.5|in|mm|adj=on|0}} rockets; the guns of the 61st Field Artillery Battalion on Los Negros;<ref name="Casey, p. 240"/> and six Kittyhawks of No.&nbsp;76 Squadron dropped {{convert|500|lb|kg|adj=on}} bombs.<ref>Odgers, ''Air War Against Japan 1943–1945'', pp. 174–175.</ref> The assault was made from three cargo-carrying LVTs. To save wear and tear, they were towed across Seeadler Harbour by LCMs and cut loose for the final run in to shore.<ref name="c2401"/> The cavalrymen found well constructed and sited bunkers with interlocking fields of fire covering all approaches, and deadly accurate snipers. The next morning an LCM brought over a medium tank, for which the Japanese had no answer, and the cavalrymen were able to overcome the defenders at a cost of eight killed and 46&nbsp;wounded; 43&nbsp;dead Japanese naval personnel were counted. The 61st and 271st Field Artillery Battalions moved to Hauwei, while the 99th established itself on Butjo Luto.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 81–82.</ref>

===Lorengau===
[[File:Admiralties-map11.JPG|thumb|right|Attack on Manus|alt=Larger scale map indicating that Los Negros is now in Allied hands. An arrow indicates an attack across the harbour, on Manus.]]
The attack on Manus got underway on 15 March. Before dawn, two troops of the [[8th Cavalry Regiment (United States)|8th Cavalry]], six cargo carrying LVTs and the combat LVT were loaded on board an LST for the {{convert|18|km|mi}} trip across Seeadler Harbour from Salami. Beaches at Lugos, about {{convert|4|km|mi}} west of Lorengau were chosen in preference to those nearer Lorengau, which were known to be heavily defended.<ref name="casey243">Casey, ''Amphibian Engineer Operations'', p. 243.</ref> The destroyers {{USS|Gillespie|DD-609|2}}, {{USS|Hobby|DD-610|2}}, {{USS|Kalk|DD-611|2}}, and {{USS|Reid|DD-369|2}} bombarded the area with their [[5"/38 caliber gun|5-inch guns]];<ref name="Gill, p. 378"/> the two rocket LCVPs, the LCM ([[flak]]), and the combat LVT raked the shoreline with rockets; the artillery on Hauwei and Butjo Luo engaged targets;<ref name="casey243" /> and 18&nbsp;B-25s of the 499th and 500th Bombardment Squadrons dropped 81&nbsp;{{convert|500|lb|kg|adj=on|0}} bombs and strafed the area.<ref>Futrell and Mortensen, "The Admiralties", in Craven and Cate (eds), ''Guadalcanal to Saipan'', p. 569.</ref>

The Japanese had evidently not expected a landing at Lugos and their positions there were quickly overrun. The 1st&nbsp;Squadron, 8th Cavalry then advanced eastward until it was stopped by a Japanese bunker complex on the edge of the Lorengau airstrip. An artillery barrage was brought down, followed by an airstrike by [[P-40 Kittyhawk]]s with 500 pound bombs. The cavalry resumed its advance, and occupied a ridge overlooking the airstrip without opposition. In the meantime, the 7th Cavalry had been landed at Lugos from the LST on its second trip and took over the defence of the area, freeing the 2nd Squadron, 8th Cavalry to join the attack on Lorengau. The first attempt to capture the airstrip was checked by an enemy bunker complex. A second attempt on 17 March, reinforced by the 1st&nbsp;Squadron, 7th&nbsp;Cavalry and tanks, made good progress. The advance then resumed, with Lorengau itself falling on 18 March.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 82–103.</ref>

Although there had been plenty of fighting, the main Japanese force on Manus had not been located. Advancing inland towards Rossum, the 7th Cavalry found it on 20 March. Six days of fighting around Rossum were required before the 7th and 8th Cavalry reduced the entrenched Japanese positions there. The Japanese bunkers, actually log and earth pillboxes, proved resistant to artillery fire.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 103–116.</ref>

===Outlying islands===
As the Japanese on Los Negros ran out of food and ammunition, the fight became increasingly unequal. A last stand by fifty Japanese in the Papitalai Hills on 24 March marked the end of organised Japanese resistance on Los Negros.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 132–133.</ref> The end of organised resistance on Los Negros and Manus still left a number of islands in Japanese hands. To minimise civilian casualties, ANGAU quietly evacuated these islands in advance of the American operations.<ref>Powell, ''The Third Force'', p. 86.</ref> Pityilu was believed occupied by about 60&nbsp;Japanese. On 30 March the 1st Squadron, 7th Cavalry was transported there from Lorengau by 10&nbsp;LCMs towing seven LVTs.<ref>Casey, ''Amphibian Engineer Operations'', p. 246.</ref> With the lessons of Hauwei in mind, the landing was covered by bombardment by destroyers, artillery, and two [[Landing Craft Support]], plus an air strike by Kittyhawks and Spitfires. The landing was unopposed, but a strong Japanese position was encountered which was overcome with the aid of artillery and tanks. Some 59&nbsp;Japanese were killed compared with eight Americans killed and six wounded.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 137–138.</ref>

The same treatment was given to Ndrilo and Koruniat on 1 April but the 1st&nbsp;Squadron, 12th&nbsp;Cavalry found them unoccupied. This was notable for being the only amphibious operation of the war carried out by the United States in dugout canoes.<ref name="casey247">Casey, ''Amphibian Engineer Operations'', p. 247.</ref> The final landing was on Rambutyo on 3 April by the 2nd&nbsp;Squadron, 12th&nbsp;Cavalry. This time, six LCMs and six LCVPs were used instead of the LVTs. As a result, the first waves grounded on a reef and troopers had to wade ashore through the surf. Fortunately for them, there was no opposition.<ref name="casey247" /> The Japanese, hiding in the interior, were eventually located by ANGAU and 30&nbsp;Japanese were killed and five captured.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 140.</ref> Patrols continued hunting for Japanese throughout the islands. Increasingly, the cavalry followed up sightings reported by the natives. On Los&nbsp;Negros, the 302nd&nbsp;Cavalry Reconnaissance Troop killed 48&nbsp;and captured 15&nbsp;Japanese during May. On Manus, some 586&nbsp;Japanese dead were counted and 47&nbsp;prisoners taken.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', pp. 143–144.</ref> General Krueger officially declared the campaign over on 18 May.<ref>Miller, ''Cartwheel: The Reduction of Rabaul'', p. 348.</ref>

===Japanese perspective===
A diary found on a dead Japanese soldier recounted his last days:
{{blockquote|'''28 March'''. Last night's duty was rather quiet except for the occasional mortar and rifle fire that could be heard. According to the conference of the various unit leaders, it has been decided to abandon the present position and withdraw. The preparation for this has been made. However, it seems as though this has been cancelled and we will firmly hold this position. Ah! This is honorable defeat and I suppose we must be proud of the way we have handled ourselves. Only our names will remain, and this is something I don't altogether like. Yes, the lives of those remaining, 300 of us, are now limited to a few days.<br />
'''30 March'''. This is the eighth day since we began the withdrawal. We have been wandering around and around the mountain roads because of the enemy. We have not yet arrived at our destination but we have completely exhausted our rations. Our bodies are becoming weaker and weaker, and this hunger is getting unbearable.<br />
'''31 March'''. Although we are completely out of rations, the march continues. When will we reach Lorengau? Or will this unit be annihilated in the mountains? As we go along, we throw away our equipment and weapons one by one.<br />
'''1 April'''. Arrived at native shack. According to a communication, friendly troops in Lorengau cannot help but withdraw. Hereafter there is no choice but to live as the natives do.<ref>Frierson, ''The Admiralties: Operations of the 1st Cavalry Division'', p. 133.</ref>}}

==Base development==

===Conflict over command===
Discussions concerning the scope and nature of base development in the Admiralty Islands were held in early February between representatives of SWPA and Admiral [[William Halsey, Jr.]]'s neighbouring [[Pacific Ocean Areas (command)|South Pacific Area (SOPAC)]]. The original intention was forces from SWPA would capture the islands and construct the airbase, while SOPAC would be responsible for the development of the naval base. The SOPAC representatives indicated they would not be able to supply troops or materials in the early stages, so it was resolved SWPA would also undertake the initial stages of naval base development.<ref>Casey, ''Airfield and Base Development'', pp. 209–210.</ref>

Admiral Nimitz recommended to the Joint Chiefs of Staff that development and control of the base facilities be placed under SOPAC by extending its border westward to include the Admiralties.<ref>James, ''The Years of MacArthur'', Volume II, pp. 388–389.</ref> MacArthur was furious; the borders of SWPA could not be changed without the consent of the Australian government.<ref>Hayes, ''The History of the Joint Chiefs of Staff in World War II: The War Against Japan'', p. 564.</ref> Nimitz's proposal was eventually turned down by the Joint Chiefs but not before MacArthur restricted access to the facilities to ships of the [[United States Seventh Fleet]] and [[British Pacific Fleet]]. Halsey was summoned to MacArthur's headquarters in Brisbane on 3 March 1944, and the two agreed to a compromise.<ref>Miller, ''Cartwheel: The Reduction of Rabaul</ref> Responsibility for the development of the base passed from Krueger's Alamo Force to Kinkaid's Allied Naval Forces on 18 May 1944. It was proposed control would ultimately pass to SOPAC but it never did.<ref>Casey, ''Airfield and Base Development'', p. 212.</ref>

===Airbase development===
Momote airfield was found to have been constructed on a coral subbase with an overburden of coconut palm [[humus]], over which the Japanese had laid a thin layer of coral and coral sand. This would not withstand heavy use, so 40th Naval Construction Battalion, 8th Engineer Squadron, and Shore Battalion of the 592nd EBSR had to strip away the humus and lay a new coral surface. Just {{convert|3600|ft}} of runway was sufficient for the Kittyhawks and Spitfires but the runway was increased to {{convert|7800|ft}} by late April.<ref>Casey, ''Airfield and Base Development'', p. 213.</ref> B-24s of [[5th Bomb Wing|5th Bombardment Group]] moved in on 18 April 1944 and flew their first mission, against [[Woleai]] two days later.<ref>Futrell, "Hollandia", in Craven and Cate (eds), ''Guadalcanal to Saipan'', p. 604.</ref>

Plans called for a second airfield at Salami Plantation, but surveys revealed that the site was unsuitable and a new site was found in a coconut plantation near [[Mokerang Airfield|Mokerang]]. While the 46th Naval Construction Battalion cleared an access road, the 836th Engineer Aviation Battalion constructed the runway, and the 104th and 46th Naval Construction Battalions built the taxiways and dispersal areas. As at Momote, the humus had to be removed to reach the coral subgrade, which was then graded and compacted. In places the coral was so hard explosives had to be used. The work required the clearing of {{convert|1100|acre|km2}} and the removal of 18,000 coconut trees.<ref name="casey216">Casey, ''Airfield and Base Development'', p. 216.</ref> B-24s of [[307th Bombardment Wing|307th Bombardment Group]] (the "Long Rangers") arrived on 21 April 1944.<ref>''Building the Navies Bases in World War II'', p. 296.</ref> They participated in raids on [[Biak]] and supported the [[Battle of Biak]] in May.<ref name="casey216" />

A fighter base to provide repair and overhaul facilities for [[aircraft carrier|carrier]] aircraft was constructed by the 78th Naval Construction Battalion on [[Ponam Island]]. As half of the work area was swamp, coral was blasted and dredged from the ocean bed and used as landfill. Another facility for carrier aircraft was built on Pityilu by the 71st Naval Construction Battalion in May and June 1944, along with accommodation for 2,500 men. The eastern end of Pityilu was cleared and a fleet recreation centre was built that could accommodate up to 10,000 at a time.<ref>''Building the Navies Bases in World War II'', pp. 301–302.</ref>

===Naval base development===
[[File:Seeadler USN drydock 1945.jpg|thumb|right|
US Navy floating Dry Dock Number{{nbsp}}4 in Seeadler Harbor in 1945|alt=A floating drydock containing ships. It is surrounded by floating barges with workshops and a tugboat.]]
Construction of the naval base on Los Negros was the responsibility of the 2nd Naval Construction Regiment, with the 11th, 58th and 71st Naval Construction Battalions. Work included a bulk storage at Papitalai for {{bbl to t|500000|lk=on}} of [[fuel oil]], {{bbl to t|100000}} of [[Diesel fuel|distillate]], {{bbl to t|76000}} of [[avgas]] and {{bbl to t|30000}} of [[gasoline|mogas]];<ref>Casey, ''Airfield and Base Development'', p. 220.</ref> a 500-bed evacuation hospital; two [[Liberty ship]] wharves; 24&nbsp;warehouses and 83&nbsp;administration buildings in [[Quonset hut]]s. At Lombrum Point, the Seabees built three installations: a [[seaplane]] repair base, a ship repair base, and a landing craft repair base. A {{convert|250|LT|t|adj=on}} pontoon drydock was provided for servicing the landing craft.<ref>''Building the Navies Bases in World War II'', pp. 296–299.</ref>

Development of facilities on Manus was taken in hand by the 5th Naval Construction Regiment, with the 35th, 44th and 57th Naval Construction Battalions, which arrived in mid-April, and the 140th Naval Construction Battalion, which was attached in June. They erected 128&nbsp;storage buildings and 50&nbsp;refrigerators, each of {{convert|680|cuft}} capacity. A water supply system was developed to supply {{convert|4000000|USgal|L}} per day. Two systems were developed, one using streams in the Lombrum area that supplied {{convert|2700000|USgal|L}} per day, and another for outlying areas that used wells to produce {{convert|850000|USgal|L}} per day. The system included water treatment plants, reservoirs, and pipes.<ref>''Building the Navies Bases in World War II'', pp. 296–301.</ref><ref>{{cite web |title=Naval records of 140th NCB (1)|url=https://www.history.navy.mil/content/dam/museums/Seabee/UnitListPages/NCB/140%20NCB.pdf|publisher=Naval History and Heritage Command |access-date=3 July 2021}}</ref><ref>Newbury, ''Down Atabrine Alley with the 140th Seabees'', pp. 3, 62</ref> All construction work was completed by April 1945, with the base remaining in use until the end of the war.<ref>Casey, ''Airfield and Base Development'', p. 222.</ref>

==Casualties==
In his final report on the campaign, General Krueger reported 3,280 Japanese dead had been counted and 75 had been captured. Perhaps 1,100 more were missing, and were never seen again. American casualties were 326&nbsp;killed, 1,189&nbsp;wounded, and four missing. Some 1,625&nbsp;Americans had been evacuated for all causes, including wounds and illness.<ref name="brewer" /> One Australian was wounded. ANGAU reported one native had been killed and one wounded in action, three were killed by the Japanese, and 20&nbsp;accidentally killed and 34&nbsp;wounded by air, artillery, and naval bombardment.<ref>ANGAU ''History of Admiralty Islands Campaign'', AWM54 80/6/6.</ref>

==Analysis==
The value of the Admiralty Islands to the Allies was enormous. Their capture saved more lives than they cost by obviating the need to capture Truk, Kavieng, Rabaul, and [[Hansa Bay]] and thereby speeding up the Allied advance by several months. As an airbase, the Admiralties' value was great, for aircraft based there ranged over Truk, Wewak, and beyond. As a naval base, their value was greater still, as they combined a fleet anchorage with major facilities.<ref>Miller, ''MacArthur and the Admiralties'', pp. 301–302.</ref>

A well-known rule of thumb is that an attacking force needs a 3:1 superiority to ensure success. In the opening stages of the battle of Los Negros, the ratio was more like 1:4. In the end the Allies won, "simply because," wrote Morison, "the United States and Australia dominated that stretch of ocean and the air over it."<ref>Morison, ''Breaking the Bismarcks Barrier'', p. 448.</ref> When queried about the naval support, General Chase replied, "they didn't support us; they saved our necks".<ref name="barbey">Barbey, ''MacArthur's Amphibious Navy'', p. 157.</ref> Chase's own defensive tactics were also a vital factor. He was awarded the [[Bronze Star Medal|Bronze Star]] for his part, as was MacArthur.<ref>Chase, ''Front Line General'', p. 59.</ref>

Allied commanders, and later historians, debated whether the Admiralty Islands Campaign was the bold action of a great commander or a reckless endeavour that courted disaster. Admiral Fechteler felt, "we're damn lucky we didn't get run off the island,"<ref>James, ''The Years of MacArthur'', Volume II, p. 387.</ref> and Admiral Barbey, for one, believed the original plan would have resulted in over-running the islands in short order with fewer casualties.<ref name="barbey" /> It would certainly have been much less risky, but it is doubtful whether an assault on the well-defended beaches of Seeadler Harbour would have resulted in fewer casualties. Whereas, in accelerating both MacArthur and Nimitz's campaigns, it shortened the war by at least a month. Thus, in the final analysis, the campaign "had the great virtue of hastening victory while reducing the number of dead and wounded".<ref>Miller, ''MacArthur and the Admiralties'', p. 302.</ref>

For the Japanese, the loss of the Admiralties meant the loss of their outpost line in the South Eastern Area. Imperial Headquarters now ordered the preparation of a new line in [[Western New Guinea]]. The Admiralties operation also indicated the Allies were becoming more ambitious and might bypass Hansa Bay. Accordingly, the [[Eighteenth Army (Japan)|Eighteenth Army]] in New Guinea was ordered to prepare to defend [[Aitape]] and [[Wewak]] as well.<ref>''Reports of General MacArthur'', Volume II, part I, pp. 248–249.</ref>

==See also==
* [[Admiralty Islands campaign order of battle]]
*[[Manus Naval Base]]

==Notes==
{{Reflist}}

==References==
{{Refbegin|30em}}
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 | author-link = Daniel E. Barbey
 | year = 1969
 | title = MacArthur's Amphibious Navy: Seventh Amphibious Force operations, 1943–1945
 | publisher = United States Naval Institute
 | location = Annapolis
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* {{cite book
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* {{cite book
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 | oclc = 220327037
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}}
* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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 | orig-date = 1946
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* {{cite book
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 |title=Vol. IV, The Pacific&nbsp;– Guadalcanal to Saipan (August 1942 to July 1944)
 |series=The Army Air Forces in World War II
 |year=1950
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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 | title=General Kenney Reports: A Personal History of the Pacific War
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 | oclc=1227801
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 | archive-date=26 February 2009
 
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* {{cite book
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 | title = From Down Under to Nippon: the Story of the 6th Army In World War II
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 | location = Lawrence, Kansas
 | isbn= 0-89839-125-3
 | oclc = 5126164
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* {{cite book
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 | oclc = 3844481
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* {{cite book
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 | title = Cartwheel: The Reduction of Rabaul
 | series = United States Army in World War II: The War in the Pacific
 | publisher = Office of the Chief of Military History, US Department of the Army
 | access-date = 5 March 2009
 | oclc = 1355535
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* {{cite book
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* {{cite book
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* {{cite book
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 |oclc        = 31189703
 |url         = https://www.history.navy.mil/content/dam/museums/Seabee/Cruisebooks/wwiicruisebooks/ncb-cruisebooks/140%20NCB.pdf
 |access-date = 3 July 2021
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* {{cite book
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* {{cite book
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* {{cite book
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* {{cite book
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 | title = The Campaigns of MacArthur in the Pacific, Volume I
 | series = Reports of General MacArthur
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* {{cite book
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 | title = Japanese Operations in the Southwest Pacific Area, Volume II&nbsp;– Part I
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 | series = Reports of General MacArthur
 | year = 1966
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 | archive-date = 7 December 2008
 | url-status = live
 | ref = none
 }}
{{Refend}}

==External links==
* [https://web.archive.org/web/20110821061724/http://media.nara.gov/google/ARC_39001.mp4 General MacArthur Leads Attack on Admiralty Islands 1944]

{{Portal bar|Australia}}

{{DEFAULTSORT:Admiralty Islands campaign}}
[[Category:1944 in Papua New Guinea]]
[[Category:Battles and operations of World War II involving Papua New Guinea]]
[[Category:Battles of World War II involving Australia]]
[[Category:Battles of World War II involving the United States]]
[[Category:Conflicts in 1944]]
[[Category:Territory of New Guinea]]
[[Category:Operation Cartwheel]]
[[Category:South West Pacific theatre of World War II]]
[[Category:February 1944 events]]
[[Category:March 1944 events]]
[[Category:April 1944 events]]
[[Category:May 1944 events]]