American Theater (World War II)
|Part of World War II|
American servicemen inspecting a shell crater after the Japanese attack on Fort Stevens, Oregon
The American Theater describes a series of mostly minor areas of operations during World War II. This was mainly due to both North and South America's geographical separation from the central theaters of conflict in Europe and Asia. Thus, any threat by the Axis Powers to invade the mainland United States or other areas was considered negligible, allowing for American resources to be deployed in overseas theaters.
This article includes attacks on continental territory, extending 200 miles (320 km) into the ocean, which is today under the sovereignty of the United States, Canada, Mexico, and several other smaller states. The best known events in North America during World War II were the Aleutian Islands Campaign, the Battle of the St. Lawrence, and the attacks on Newfoundland.
- 1 German operations
- 1.1 South America
- 1.2 United States
- 1.3 German landings in Canada
- 1.4 German landings in Newfoundland
- 1.5 U-Boat operations
- 2 Japanese operations
- 3 Cancelled Axis operations
- 4 Other alarms
- 5 See also
- 6 Notes
- 7 Further reading
- 8 External links
- Battle of the River Plate
The first naval battle during the war was fought on December 13, 1939 off the Atlantic coast of South America. The German "pocket battleship" Admiral Graf Spee (acting as a commerce raider) encountered one of the British naval units searching for her. Composed of three Royal Navy cruisers, HMS Exeter, Ajax, and Achilles, the unit was patrolling off the River Plate estuary of Argentina and Uruguay. In a bloody engagement, the Graf Spee repulsed the British attacks; however, Captain Hans Langsdorff brought his damaged ship to shelter in neutral Uruguay. British intelligence successfully deceived Langsdorff into believing that a much superior British force had gathered to wait for him, and so he scuttled his ship at Montevideo to save his crew's lives. German combat losses were 96 killed or wounded, against 72 British sailors killed and 28 wounded. The Royal Navy had two cruisers severely damaged, but it had cost the German navy one of its finest ships.
Duquesne Spy Ring
Even before the war, a large Nazi spy ring was found operating in the United States. The Duquesne Spy Ring is still the largest espionage case in United States history that ended in convictions. The 33 German agents who formed the Duquesne spy ring were placed in key jobs in the United States to get information that could be used in the event of war and to carry out acts of sabotage. One man opened a restaurant and used his position to get information from his customers; another worked at an airline so he could report Allied ships crossing the Atlantic Ocean; others in the ring worked as deliverymen so they could deliver secret messages alongside normal messages. The ring was led by Captain Fritz Joubert Duquesne, a South African Boer who spied for Germany in both World Wars and is best known as "The man who killed Kitchener" after he was awarded the Iron Cross for his key role in the sabotage and sinking of HMS Hampshire in 1916. William G. Sebold, a double agent for the United States, was a major factor in the FBI's successful resolution of this case. For nearly two years, Sebold ran a radio station in New York for the ring, giving the FBI valuable information on what Germany was sending to its spies in the United States while also controlling the information that was being transmitted to Germany. On June 29, 1941, the FBI closed in. All 33 spies were arrested, found guilty, and sentenced to serve a total of over 300 years in prison.
Upon declaring war on the United States, Adolf Hitler ordered the remaining German saboteurs to wreak havoc on America. The responsibility for carrying this out was given to German Intelligence (Abwehr). In the spring of 1942, nine agents were recruited (one eventually dropping out) and divided into two teams: the first, commanded by George John Dasch, with Ernst Peter Burger, Heinrich Heinck, and Richard Quirin; the second, under the command of Edward Kerling, with Hermann Neubauer, Werner Thiel, and Herbert Haupt.
On June 12, 1942, the U-boat U-202 landed Dasch's team with explosives and plans at East Hampton, Long Island, New York. Their mission was to destroy power plants at Niagara Falls and three Aluminum Company of America (ALCOA) factories in Illinois, Tennessee, and New York. Dasch instead turned himself in to the FBI, providing them with a complete account of the planned mission, which led to the arrest of the entire team.
Kerling's team landed from U-584 at Ponte Vedra Beach (25 miles [40 km] south-east of Jacksonville, Florida), on June 17. They were tasked with laying mines in four areas: the Pennsylvania Railroad in Newark, New Jersey, canal sluices in both St. Louis and Cincinnati, and New York City's water supply pipes. The team made their way to Cincinnati, Ohio and split up, with two going to Chicago, Illinois, and the others to New York. The Dasch confession led to the arrest of all of the men by July 10.
Because the Germans were captured in civilian clothes, they were tried by a military tribunal in Washington D.C., with six men sentenced to death for spying. President Franklin D. Roosevelt approved the sentences. The constitutionality of military tribunals was upheld by the U.S. Supreme Court in Ex parte Quirin on July 31, and the six men were executed by electrocution at the D.C. jail on August 8. Dasch and Burger were given thirty-year prison sentences because they had turned themselves in to the FBI and provided information about the others. Both were released in 1948 and deported to Germany. Dasch (aka George Davis), who had been a longtime American resident before the war, suffered a difficult life in Germany after his return from U.S. custody because of his cooperation with U.S. authorities. As a condition of his deportation, he was not permitted to return to the United States, even though he spent many years writing letters to prominent American authorities (J. Edgar Hoover, President Eisenhower, etc.) seeking permission to return. He eventually moved to Switzerland and wrote a book, titled Eight Spies Against America.
In 1944 there was another attempt at infiltration, codenamed Operation Elster ("Magpie"). Elster involved Erich Gimpel and German-American defector William Colepaugh. Their mission objective was to gather intelligence on the Manhattan Project and attempt sabotage if possible. The pair sailed from Kiel on U-1230 and landed at Hancock Point, Maine on November 30, 1944. Both made their way to New York, but the operation degenerated into total failure. Colepaugh turned himself in to the FBI on December 26, confessing the whole plan; Gimpel was arrested four days later in New York. Both men were sentenced to death but eventually had their sentences commuted. Gimpel spent 10 years in prison; Colepaugh was released in 1960 and operated a business in King of Prussia, Pennsylvania before retiring to Florida.
German landings in Canada
St. Martins, New Brunswick
One month earlier than the Dasch operation (on May 14, 1942), a solitary Abwehr agent, Marius A. Langbein, was landed by a U-boat (U-217) near St. Martins, New Brunswick, Canada. His mission, codenamed Operation Grete, after the name of the agent's wife, was to observe and report shipping movements at Montreal and Halifax, Nova Scotia (the main departure port for North Atlantic convoys). Langbein, who had lived in Canada before the war, changed his mind and moved to Ottawa, where he lived off his Abwehr funds until he surrendered to the Canadian authorities in December 1944. A jury found Langbein not guilty of spying, since he had never committed any hostile acts against Canada during the war.
New Carlisle, Quebec
In November 1942, U-518 sank two iron ore freighters and damaged another off Bell Island in Conception Bay, Newfoundland, en route to the Gaspé Peninsula where, despite an attack by a Royal Canadian Air Force aircraft, it successfully landed a spy, Werner von Janowski, four miles (6.5 km) from New Carlisle, Quebec at around 5am on November 9, 1942.
Von Janowski showed up at the New Carlisle Hotel at 6:30am asking for a room with a bath. The son of the hotel manager, Earle Annett Jr., noticed that the stranger seemed preoccupied and quickly noticed some inconsistencies in his story. The man said he took the bus that morning before walking to the hotel; but in fact the bus was not going through New Carlisle that day, and even if it had, it would have dropped him off at the hotel. Annett also noticed that he spoke English with a Parisian accent, his clothing had European styling, and that he paid for his cigarettes with an obsolete Canadian dollar bill that had not been in circulation for quite some time. The stranger also had a strange smell on him; he was using Belgian matches that did not carry the Canadian government seal that was applied to matchbooks at the time. Less than three hours after his arrival and before Annett could confirm his suspicions, the stranger paid his bill and made his way to the train station where he had a coffee while waiting for the next train.
Annett followed him to the station, sat down beside him, and offered some cigarettes. Von Janowski lit the cigarette using the same Belgian matches he had at the hotel. Annett grew even more suspicious and then alerted a Quebec Provincial Police constable, who quickly boarded the train as it pulled away from the station and began searching for the stranger. The policeman located Von Janowski, who said he was a radio salesman from Toronto. He stuck with this story until the policeman asked to search his bags; the stranger then confessed: "That will not be necessary. I am a German officer who serves his country as you do yourself."  Inspection of Janowski's personal effects upon his arrest revealed that he was carrying a powerful radio transmitter, among other things.
Janowski spent the next year as a double agent, codenamed WATCHDOG by the Allies and Bobbi by the Abwehr, sending false messages to Germany under the joint control of the RCMP and MI5, with spymaster Cyril Mills having been seconded to Canada to assist in the double cross initiative. The effectiveness and honesty of his "turn" is a matter of some dispute. For example, John Cecil Masterman writes in The Double Cross System: "In November, WATCHDOG was landed from a U-boat in Canada together with a wireless set and an extensive questionnaire. This move on the part of the Germans threatened an extension of our activities to other parts of the world, but in fact the case did not develop very satisfactorily... WATCHDOG was closed down in the summer [of 1943]."
German landings in Newfoundland
Weather Station Kurt, Martin Bay
Accurate weather reporting was important to the sea war and on September 18, 1943, U-537 sailed from Kiel, via Bergen, Norway, with a meteorological team led by Professor Kurt Sommermeyer. They landed at Martin Bay, a remote location near the northern tip of Labrador on October 22, 1943 and successfully set up an automatic weather station ("Weather Station Kurt" or "Wetter-Funkgerät Land-26"), despite the constant risk of Allied air patrols. The station was powered by batteries that were expected to last about three months. At the beginning of July 1944, U-867 left Bergen to replace the equipment, but was sunk en route. The weather station remained at the site until it was recovered in the 1980s and placed in the Canadian War Museum.
The Atlantic Ocean was a major strategic battle zone (the "Battle of the Atlantic") and when Germany declared war on the U.S., the East Coast of the United States offered easy pickings for German U-Boats (referred to as the "Second Happy Time"). After a highly successful foray by five Type IX long-range U-boats, the offensive was maximized by the use of short-range Type VII U-boats, with increased fuel stores, replenished from supply U-boats called Milchkühe (milk cows). From February to May 1942, 348 ships were sunk, for the loss of 2 U-boats during April and May. U.S. naval commanders were reluctant to introduce the convoy system that had protected trans-Atlantic shipping[clarification needed] and, without coastal blackouts, shipping was silhouetted against the bright lights of American towns and cities such as Atlantic City until a dim-out was ordered in May.
The cumulative effect of this campaign was severe; a quarter of all wartime sinkings – 3.1 million tons. There were several reasons for this. The naval commander, Admiral Ernest King, as an apparent anglophobe, was averse to taking British recommendations to introduce convoys, U.S. Coast Guard and Navy patrols were predictable and could be avoided by U-boats, inter-service co-operation was poor, and the U.S. Navy did not possess enough suitable escort vessels (British and Canadian warships were transferred to the U.S. east coast).
Several ships were torpedoed within sight of East Coast cities such as New York and Boston. The only documented World War II sinking of a U-boat close to New England shores occurred on May 5, 1945, when the U-853 torpedoed and sank the collier Black Point off Newport, Rhode Island. When the Black Point was hit, the U.S. Navy immediately chased down the sub and began dropping depth charges. In recent years, the U-853 has become a popular dive site. Its intact hull, with open hatches, is located in 130 feet (40 m) of water off Block Island, Rhode Island. A wreck discovered in 1991 off the New Jersey coast was concluded in 1997 to be that of U-869. Previously, U-869 had been thought to have been sunk off Rabat, Morocco.
Gulf of Mexico
Once convoys and air cover were introduced in the Atlantic, sinking numbers were reduced and the U-boats shifted to attack shipping in the Gulf of Mexico. During 1942 and 1943, more than 20 U-boats operated in the Gulf of Mexico. They attacked tankers transporting oil from ports in Texas and Louisiana, successfully sinking 56 vessels. By the end of 1943, the U-boat attacks diminished as the merchant ships began to travel in armed convoys.
In one instance, the tanker Virginia was torpedoed in the mouth of the Mississippi River by the German U-Boat U-507 on May 12, 1942, killing 26 crewmen. There were 14 survivors. Again, when defensive measures were introduced, ship sinkings decreased.
U-166 was the only U-boat sunk in the Gulf of Mexico during the war. Once thought to have been sunk by a torpedo dropped from a U.S. Coast Guard Utility Amphibian J4F aircraft on August 1, 1942, U-166 is now believed to have been sunk two days earlier by depth charges from the passenger ship SS Robert E. Lee’s naval escort, the U.S. Navy sub-chaser, PC-566. It is thought that the J4F aircraft may have spotted and attacked another German submarine, U-171, which was operating in the area at the same time. U-166 lies in 5,000 feet of water within a mile of her last victim, the SS Robert E. Lee.
From the start of the war in 1939 until VE Day, several of Canada's Atlantic coast ports became important to the resupply effort for the United Kingdom and later for the Allied land offensive on the Western Front. Halifax and Sydney, Nova Scotia became the primary convoy assembly ports, with Halifax being assigned the fast or priority convoys (largely troops and essential material) with the more modern merchant ships, while Sydney was given slow convoys which conveyed bulkier material on older and more vulnerable merchant ships. Both ports were heavily fortified with shore radar emplacements, search light batteries, and extensive coastal artillery stations all manned by RCN and Canadian Army regular and reserve personnel. Military intelligence agents enforced strict blackouts throughout the areas and anti-torpedo nets were in place at the harbor entrances, making a direct attack on those facilities unfeasible due to the impossibility for Germany to provide air support. Despite the fact that no landings of German personnel took place near these ports, there were frequent attacks by U-boats on convoys departing for Europe once these had reached the mouth of the St. Lawrence. Less extensively used, but no less important, was the port of Saint John which also saw matériel funneled through the port, largely after the United States entered the war in December 1941. The port's location within the protected waters of the Bay of Fundy made it a difficult target for attack. The Canadian Pacific Railway mainline from central Canada (which crossed the state of Maine) could be used to transport in aid of the war effort.
Although not crippling to the Canadian war effort, given the country's rail network to the east coast ports, but possibly more destructive to the morale of the Canadian public, was the Battle of the St. Lawrence, when U-boats began to venture upriver and attack domestic coastal shipping along Canada's east coast in the St. Lawrence River and Gulf of St. Lawrence from early 1942 through to the end of the shipping season in late 1944. From a German perspective this area contained most of the military assets in North America that could be realistically be targeted for attack, and therefore the St.Lawrence was the only zone that saw consistent warfare -albeit on a limited scale- in North America during World War II.Residents along the Gaspé coast and the St. Lawrence River and Gulf of St. Lawrence were startled at the sight of maritime warfare off their shores, with ships on fire and explosions rattling their communities, while bodies and debris floated ashore. The number of military losses is not known, although loose estimates can be made based on the number of surface units and submarines sunk.
Five significant attacks on Newfoundland took place in 1942. On 3 March 1942, U-587 fired three torpedoes at St. John’s; one hit Fort Amherst and two more hit the cliffs of Signal Hill below Cabot Tower. In autumn German U-boats attacked four iron ore carriers serving the DOSCO iron mine at Wabana on Bell Island in Newfoundland's Conception Bay. The ships SS Saganaga and SS Lord Strathcona were sunk by U-513 on 5 September 1942, while SS Rosecastle and P.L.M 27 were sunk by U-518 on 2 November with the loss of 69 lives. After the sinkings the submarine fired a torpedo that missed its target, the 3,000-ton collier Anna T, and struck the DOSCO loading pier and exploded. On 14 October 1942, the Newfoundland Railway ferry SS Caribou was torpedoed by U-69 and sunk in the Cabot Strait south of Port aux Basques. Caribou was carrying 45 crew and 206 civilian and military passengers. 137 lost their lives, many of them Newfoundlanders. Half a dozen U-boat wrecks lie in what are today Canadian waters around Newfoundland and Labrador, due to Canadian patrols. It had shown the people in Newfoundland that the war had come to their doorstep. One U-boat wreck has been found as far as Muskrat Falls in Labrador.
A German submarine shelled the American Standard Oil refinery at the San Nicolas harbour and the "Arend"/"Eagle" Maatschappij (from the Dutch/British Shell Co.) near the Oranjestad harbour situated on the Island of Aruba (a Dutch colony) and some ships that were near the entrance to Lake Maracaibo on February 16, 1942. Three tankers, including the Venezuelan Monagas, were sunk. A Venezuelan gunboat, General Urbaneta, assisted in rescuing the crews.
Aleutian Islands Campaign
On June 3-4 1942, Japanese planes from two light carriers Ryūjō and Jun'yō struck the U.S. military base at Dutch Harbor in the Aleutian Islands, Unalaska, Alaska. Originally, the Japanese planned to attack Dutch Harbor simultaneously with its attack on Midway but it occurred a day earlier due to one-day delay. The attack only did moderate damage on Dutch Harbor and 78 Americans were killed in the attack.
On June 6, two days after the bombing of Dutch Harbor, 500 Japanese marines landed on Kiska, one of the Aleutian Islands of Alaska. Upon landing, they killed two and captured eight U.S. Navy officers, then took the remaining inhabitants of the island, and quickly took control of American soil. The next day on June 7, a strength of 1,140 Japanese infantrymen landed on Attu via Holtz Bay, ending up eventually at Massacre Bay and Chichagof Harbor. At this time, Attu's population consisted of several Blue Fox, 45 native Aleuts, and two Americans: Charles Foster Jones, a 60 year old ham radio operator and weather observer, and his 62 year old wife Etta Jones, a teacher and trained nurse. Mr. Jones was killed after being interrogated by the Japanese while Mrs. Jones along with the remaining Aleut population were held prisoners and sent to Japan. These invasions marked the second time that American soil was under occupation by a foreign enemy, the first being the War of 1812 by the British.
A year after Japan's invasion and occupation of the islands of Attu and Kiska, 34,000 U.S. troops invaded these islands and fought there throughout the summer, defeated the Japanese, and eventually reestablished control of the islands.
West Coast and Alaska
|This section does not cite any references or sources. (March 2013)|
Several ships were torpedoed within sight of West Coast Californian cities such as Los Angeles, Santa Barbara, San Diego, and Santa Monica. During 1941 and 1942, more than 10 Japanese submarines operated in the West Coast, Alaska, and Baja California. They attacked American, Canadian, and Mexican ships, successfully sinking over 10 vessels including the Soviet Navy submarine L-16 on October 11, 1942.
Bombardment of Ellwood
The United States mainland was first shelled by the Axis on February 23, 1942 when the Japanese submarine I-17 attacked the Ellwood Oil Field west of Goleta, near Santa Barbara, California. Although only a pumphouse and catwalk at one oil well were damaged, I-17 captain Nishino Kozo radioed Tokyo that he had left Santa Barbara in flames. No casualties were reported and the total cost of the damage was officially estimated at approximately $500–1,000. News of the shelling triggered an invasion scare along the West Coast.
Bombardment of Estevan Point Lighthouse
More than 5 Japanese submarines operated in Western Canada during 1941 and 1942. On June 20, 1942, the Japanese submarine I-26, under the command of Yokota Minoru, fired 25–30 rounds of 5.5" shells at the Estevan Point lighthouse on Vancouver Island in British Columbia, but failed to hit its target. Though no casualties were reported, the subsequent decision to turn off the lights of outer stations was disastrous for shipping activity.
Bombardment of Fort Stevens
In what became the only attack on a mainland American military installation during World War II, the Japanese submarine I-25, under the command of Tagami Meiji, surfaced near the mouth of the Columbia River, Oregon on the night of June 21 and June 22, 1942, and fired shells toward Fort Stevens. The only damage officially recorded was to a baseball field's backstop. Probably the most significant damage was a shell that damaged some large phone cables. The Fort Stevens gunners were refused permission to return fire for fear of revealing the guns' location and/or range limitations to the sub. American aircraft on training flights spotted the submarine, which was subsequently attacked by a US bomber, but escaped.
Lookout Air Raids
The Lookout Air Raids occurred on September 9, 1942. The only aerial bombing of mainland America by a foreign power occurred when an attempt to start a forest fire was made by a Japanese Yokosuka E14Y1 "Glen" seaplane dropping two 80 kg (180 lb) incendiary bombs over Mount Emily, near Brookings, Oregon. The seaplane, piloted by Nobuo Fujita, had been launched from the Japanese submarine aircraft carrier I-25. No significant damage was officially reported following the attack, nor after a repeat attempt on September 29.
Fire balloon attacks
Between November 1944 and April 1945, the Japanese Navy launched over 9,000 fire balloons toward North America. Carried by the recently discovered Pacific jet stream, they were to sail over the Pacific Ocean and land in North America, where the Japanese hoped they would start forest fires and cause other damage. About three hundred were reported as reaching North America, but little damage was caused. Six people (five children and a woman) became the only deaths due to enemy action to occur on mainland America during World War II when one of the children tampered with a bomb from a balloon near Bly, Oregon and it exploded. The site is marked by a stone monument at the Mitchell Recreation Area in the Fremont-Winema National Forest. Recently released reports by the Royal Canadian Mounted Police and the Canadian military indicate that fire balloons reached as far inland as Manitoba. A fire balloon is also considered to be a possible cause of the third fire in the Tillamook Burn. One member of the 555th Parachute Infantry Battalion died while responding to a fire in the Northwest on August 6, 1945; other casualties of the 555th were two fractures and 20 other injuries.
Cancelled Axis operations
Just after the attack on Pearl Harbor, a force of seven Japanese submarines patrolled the United States West Coast. The wolf pack made plans to bombard targets in California on Christmas Eve of 1941. However, the attack was postponed to December 27 and then canceled due to fears of American reprisal.
The Japanese constructed a plan early in the Pacific War to attack the Panama Canal, a vital water passage in Panama, used during World War II primarily for the Allied supply effort. The Japanese attack was never launched due to crippling naval losses at the beginning of conflict with the United States and United Kingdom (See: Aichi M6A).
Imperial Japanese Army launched Project Z (also called the Z Bombers Project) in 1942, similar to the Nazi German Amerika Bomber project, to design an intercontinental bomber capable of reaching North America. The Project Z plane was to have six engines of 5,000 horsepower each; the Nakajima Aircraft Company quickly began developing engines for the plane, and proposed doubling HA-44 engines (the most powerful engine available in Japan) into a 36-cylinder engine. Designs were presented to the Imperial Japanese Army, including the Nakajima G10N, Kawasaki Ki-91, and Nakajima G5N. None developed beyond prototypes or wind tunnel models, save for the G5N. In 1945, the Z project and other heavy bomber projects were cancelled.
In 1940, the German Air Ministry requested designs of the major German aircraft companies for its Amerika Bomber program, in which a long-range strategic bomber would strike the continental United States from the Azores. Planning was complete in 1942, but the project was abandoned as too expensive.
Hitler had ordered that biological warfare should be studied only for the purpose of defending against it. The head of the Science Division of the Wehrmacht, Erich Schumann, lobbied for Hitler to be persuaded otherwise: "America must be attacked simultaneously with various human and animal epidemic pathogens, as well as plant pests." The plans were never adopted due to opposition by Hitler.
These false alarms have generally been attributed to military and civilian inexperience with war and poor radars of the era. Critics have theorized they were a deliberate attempt by the Army to frighten the public in order to stimulate interest in war preparations.
Alerts following Pearl Harbor
On December 8, 1941 rumors of an enemy carrier off the coast led to the closing of schools in Oakland, California, a blackout enforced by local wardens and radio silence followed that evening. The reports reaching Washington of an attack on San Francisco were regarded as credible. The affair was described as a test but Lt. Gen. John L. DeWitt of the Western Defense Command said “Last night there were planes over this community. They were enemy planes! I mean Japanese planes! And they were tracked out to sea. You think it was a hoax? It is damned nonsense for sensible people to assume that the Army and Navy would practice such a hoax on San Francisco.” Rumors continued on the west coast in the following days. An alert of a similar nature occurred in the Northeast on December 9. At noon advices were received that hostile planes were only two hours’ distance away. Although there was no general hysteria, fighter aircraft from Mitchel Field on Long Island took the air to intercept the "raiders". Wall Street had its worst sell off since the fall of France, school children in New York City were sent home and several radio stations left the air. In Boston police shifted heavy stores of guns and ammunition from storage vaults to stations throughout the city, and industrial establishments were advised to prepare for a raid.
Battle of Los Angeles
The Battle of Los Angeles also known as "The Great Los Angeles Air Raid" is the name given by contemporary sources to the imaginary enemy attack and subsequent anti-aircraft artillery barrage which took place in 1942 from February 24 and early on February 25 over Los Angeles, California. Initially, the target of the aerial barrage was thought to be an attacking force from Japan, but Secretary of the Navy Frank Knox speaking at a press conference shortly afterward called the incident a "false alarm." Newspapers of the time published a number of sensational reports and speculations of a cover-up. When documenting the incident in 1983, the U.S. Office of Air Force History attributed the event to a case of "war nerves" likely triggered by a lost weather balloon and exacerbated by stray flares and shell bursts from adjoining batteries.
In May and June the San Francisco Bay Area underwent a series of alerts:
- May 12: A twenty-five minute air-raid alert.
- May 27: West Coast defenses put on alert after Army codebreakers learned that the Japanese intended a series of hit-and-run attacks in reprisal for the Doolittle Raid.
- May 31: The battleships USS Colorado and USS Maryland set sail from the Golden Gate to form a line of defense against any Japanese attack mounted on San Francisco.
- June 2: A nine-minute air-raid alert, including at 9:22 pm a radio silence order applied to all radio stations from Mexico to Canada.
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- Beebe, Dean, Cargo of Lies: The True Story of a Nazi Double Agent in Canada, University of Toronto Press, 1996 isbn 0-8020-0731-7
- Dobbs, Michael. Saboteurs: The Nazi Raid on America ISBN 0-375-41470-3 (2004)
- Duffy, J.P. TARGET: AMERICA, Hitler's Plan to Attack the United States, Praeger Publishers; PB: The Lyons Press (A Booklist review)
- Gimpel, Erich. Agent 146: The True Story of a Nazi Spy in America ISBN 0-312-30797-7 (2003)
- Griehl, Manfred. Luftwaffe over America: The Secret Plans to Bomb the United States in World War II ISBN 1-85367-608-X (2004)
- Hadley, Michael (1985). U-Boats against Canada: German Submarines in Canadian Waters. McGill Queens University Press. ISBN 0-7735-0801-5.
- Horn, Steve (2005), The Second Attack on Pearl Harbor: Operation K And Other Japanese Attempts to Bomb America in World War II, Naval Institute Press, ISBN 1-59114-388-8
- Mikesh, Robert C. Japan's World War II Balloon Bomb Attacks on North America, Smithsonian Institution Press, (1973)
- Kesich, Gregory D. (April 13, 2003), 1944: When spies came to Maine, Portland Press Herald, archived from the original on 2007-09-22, retrieved 2007-12-09
- O'Donnell, Pierce, In Time of War: Hitler's Terrorist Attack on America (Operation Pastorius), The New Press, 2005 isbn 1-56854-958-2
- Webber, Bert. Silent Siege: Japanese Attacks Against North America in World War II, Ye Galleon Press, Fairfield, Washington (1984). ISBN 0-87770-315-9 (hardcover). ISBN 0-87770-318-3 (paperbound).
- O'Hara, Vincent (2004). The German fleet at war, 1939–1945. Naval Institute Press.
- American targets
- Japanese submarine attacks
- German Sabotage operations
- Planned Italian attack on New York harbour.
- The Bay Area at War
- Army Responses
- Details of German secret agents landed in North America
- Red White Black & Blue – feature documentary about The Battle of Attu in the Aleutians during World War II
- Defense of Americas a publication of the United States Army Center of Military History
- The Battle of the St. Lawrence