Armed merchantman is a term that has come to mean a merchant ship equipped with guns, usually for defensive purposes, either by design or after the fact. In the days of sail, piracy and privateers, many merchantmen would be routinely armed, especially those engaging in long distance and high value trade. The most famous of this type were the East Indiamen able to defeat regular warships in battle (see Battle of Pulo Aura). In more modern times, auxiliary cruisers were used offensively to disrupt trade chiefly during both World War I and World War II, particularly by Germany.
- 1 Pre-20th century
- 2 20th century
- 3 Ship lists
- 3.1 Spanish-American War
- 3.2 Russo-Japanese War
- 3.3 World War I
- 3.4 Spanish Civil War
- 3.5 World War II
- 4 21st century
- 5 See also
- 6 References
- 7 External links
East Indiamen of various European countries were heavily armed for their long journeys to the Far East. In particularly dangerous times, such as when the home countries were at war, a convoy system would be used whereby the ships were escorted by a warship. However, many East Indiamen also travelled on their own, and therefore were heavily armed in order to defend themselves against pirates and privateers. They also defended themselves against warships, scoring signal victories at the Battle of Pulo Aura and the Action of 4 August 1800. The British Royal Navy purchased several that it converted to ships of the line.
In 1856, privateering (or seizure of a belligerent country's merchant ships as a private enterprise) lost international sanction under the Declaration of Paris. From 1861-65 European countries built high speed ships to run the Union Blockade during the American Civil War. Some of these were armed and served as Confederate States Navy raiders.
Russia purchased three ships in 1877 of 6,000 long tons (6,100 t) armed with 6-inch (150 mm) guns for use as auxiliary cruisers for a Russian Volunteer Fleet. Germany and the United Kingdom responded to the precedent by asking their shipping companies to design fast steamers with provision for mounting guns in time of war.
- 1890 - German and British shipyards built new civilian ships designed for wartime conversion, and France, Italy, Japan, Austria-Hungary, and the United States made similar agreements with their shipyards.
Russia built two more auxiliary cruisers in 1892.
In 1895 the Imperial German Navy mobilized the provisional auxiliary cruiser Normannia for a 15-day trial armed with eight 6-inch guns, two 3.5-inch (89 mm) guns, six 37-millimetre (1.46 in) guns, and two torpedo boats.
In both World Wars both Germany and the United Kingdom used auxiliary cruisers. Whilst the British used armed passenger liners defensively for protecting their shipping, the German approach was to use them offensively to attack enemy shipping.
Armed merchant cruisers
The Armed Merchant Cruisers (AMC) of the British Royal Navy were employed for convoy protection against enemy warships. They ultimately proved to have limited value and many (particularly liners) were later converted into troopships, a role for which they were more suited. Documentary evidence quoted by the BBC researched from the early stages of the First World War suggests that the express liners had greater speed than most warships- few warships of the period could exceed 21 knots -which made them suitable as AMC's. The downside proved to be their high fuel consumption, and that that using them in a purely AMC role would have burned through the Admiralty reserve supplies of steam coal in less than three months. The ships were vulnerable to enemy fire because they lacked warship armour and they used local control of guns rather than director fire-control systems, which reduced their effective fire power.
One famous AMC of World War I was the British RMS Carmania which, after a heated battle that caused heavy damage on both sides, succeeded in sinking the German auxiliary cruiser SMS Cap Trafalgar near the Brazilian island of Trinidade in 1914. By coincidence, Cap Trafalgar was disguised as Carmania.
In World War II, HMS Jervis Bay—the sole escort for convoy HX 84 in November 1940— stood off the pocket battleship Admiral Scheer, when the German ship attacked the convoy. Though she was sunk, this enabled the convoy to escape. Her master, Acting Captain Edward Fegen was awarded the Victoria Cross (posthumous) for his actions. Another famous action involving an armed merchant cruiser was the November 1939 battle between HMS Rawalpindi and the German battlecruisers Scharnhorst and Gneisenau. Fighting against hopeless odds, the Rawalpindi was quickly sunk.
Both the Spanish and United States Navy used auxiliary cruisers during the Spanish-American War of 1898. In World War I too, American auxiliary cruisers fought several engagements with German U-boats.
The German practice was to arm merchantmen with hidden weapons and use them as commerce raiders. An auxiliary cruiser—Hilfskreuzer or Handels-Stör-Kreuzer (HSK)—usually approached her target under a false flag with guns concealed, and sometimes with her appearance altered with fake funnels and masts and often a fake paint job. The victim was thus engaged at point-blank range and had no chance to escape. In World War I, the Imperial German Navy initially used fast passenger ships (such as past holders of the Blue Riband for fastest North Atlantic crossings), but they made obvious and easy targets because of their very familiar silhouettes. The Germans therefore soon moved on to using captured and refitted Allied vessels, but principally only modified transport ships. These were slower, but less recognizable. In both world wars, these ships were vulnerable to attack, and were withdrawn before the war ended. Many were sunk after being caught by regular warships—an unequal battle since auxiliary cruisers had poor fire control and no armor. There were, however, a few success stories. Kaiser Wilhelm der Grosse was a former passenger liner that sank two freighters in 1914 before being caught by HMS Highflyer. Her sister ship, Kronprinz Wilhelm, had a legendary journey, sinking or capturing a total of 15 ships in 1914 and 1915, before finally running out of supplies and having to put into port in Virginia, where the Americans interned her and eventually converted her into the United States Navy troop transport USS Von Steuben. The most famous German commerce raider of World War I probably was Seeadler, a sailing ship under the command of the legendary Count Felix von Luckner. However, both Wolf and Möwe were each much more successful than Seeadler.
In World War II, the German Navy operated ten very successful auxiliary cruisers which ranged in tonnage from 3,860-9,400; typically these vessels were equipped with:
- 6 in (15 cm) guns
- Smaller armaments (typically hidden away behind specially designed and hinged bulwarks, or beneath fake deckhouses and/or skylights)
To preserve their cover, these ships flew the flags of neutral or occasionally Allied nations. They re-fuelled and provisioned themselves from special supply ships, from Japanese island bases, or simply from prizes they had taken.
In one incident, the German Kormoran (ex-merchantman Steiermark) managed to surprise and sink the Australian light cruiser HMAS Sydney, which approached too close, though Kormoran herself was also sunk in the engagement. This was the only occasion in history when an armed merchantman managed to sink a modern warship; in most cases, auxiliary cruiser raiders tried to avoid confrontation with warships. It should be noted that Kormoran's attack upon Sydney was motivated by desperation. However, she was not the most successful German raider of World War II (both Atlantis and Pinguin scored higher kill tonnages). Another, Stier, was also sunk in a mutually destructive engagement with the American Liberty ship SS Stephen Hopkins.
The only encounters between Allied and Axis auxiliary cruisers in World War II were all with the raider Thor. This small vessel, which captured or sank 22 merchantmen, encountered three British AMCs in her career, defeating HMS Alcantara and HMS Carnarvon Castle and later sinking HMS Voltaire.
During World War II, German auxiliary cruisers are believed to have either sunk or captured some 800,000 long tons (810,000 t) of Allied shipping.
Compare to the Q-ship, which was a disguised merchantman for anti-submarine operations.
The CAM Ship (from catapult armed merchantman) was a British merchantman fitted with a catapult that could launch, but not recover, a single fighter aircraft.
The Merchant Aircraft Carrier or MAC was a British or Dutch cargo ship with a flight deck that could carry a small number of aircraft.
American auxiliary cruisers
|Harvard||(ex-New York, ex-City of New York)|
Japanese merchant cruisers
|Hong Kong Maru|
Russian merchant cruisers
Note: This listing is incomplete.
World War I
Allied merchant cruisers
|Alcantara||Lost on 29 February 1916.|
|Almanzora||In service 23Aug.15-20.Dec.19. 1 of over 60 commissioned AMC's employed on patrol and later convoy protection, 33 served with 10th Cruiser Squadron on Northern Patrol.|
|Alsatian||Post war, Allan line was taken over by CP and SS Alsatian was named RMS Empress of France 4 April 1919.|
|Ambrose||Became depot ship October 1915.|
|Avenger||Ex-Aotearoa, torpedoed and lost on 14 June 1917.|
|Bayano||Lost on 11 March 1915 off Carswell Point, Stranraer - sunk by U-27.|
|Calgarian||Lost on 1 March 1918.|
|Calyx||Ex-Calypso, lost 10 July 1916.|
|Candidate||Torpedoed 6 May 1915, sunk by U-20|
|Caribbean||Became accommodation ship July 1915, foundered 26 September 1915.|
|Centurion||Torpedoed 6 May 1915, sunk by U-20|
|City of London|
|Clan MacNaughton||Lost on 3 February 1915.|
|Columbella||Ex-Columbia, Anchor Line.|
|Digby||Transferred to French Navy as Artois on 24 November 1915, renamed Digby July 1917.|
|Empress of Asia|
|Empress of Britain|
|Empress of Japan|
|Empress of Russia||Requisitioned 1914, released to civilian service October 1915, re-requisitioned 1918 until 1919.|
|Eskimo||Returned from Navy July 1915, Captured 26 July 1916.|
|Hilary||Lost on 25 May 1917, sunk by U-88.|
|India||Lost on 8 August 1915.|
|Laconia||Lost on 25 February 1917, sunk by U-50.|
|Laurentic||Lost on 23 January 1917.|
|Lusitania||Although on the list of the British Admiralty's AMCs, it never performed in this role, and remained in civilian use. Lost 7 May 1915, sunk by U-20. Sister ship of RMS Mauretania, also on this list.|
|Marmora||Lost on 23 July 1918.|
|Mauretania||Sister ship of RMS Lusitania, also on this list.|
|Moldavia||Lost on 23 May 1918.|
|Montezuma||Lost on 25 July 1917, sunk by UC-41.|
|Mount Temple||Lost on 6 December 1916, sunk by Möwe.|
|Narkunda||Was serving as an auxiliary transport during the Allied landings in French North Africa in November, 1942. She had disembarked her troops at Bougie and had turned about for home when, toward evening on the 14th, she was bombed and sunk some distance off Bougie. Thirty-one persons were killed. Capt. Parfitt was among the survivors.|
|Oceanic||Lost on 8 September 1914, ran aground. RMS Oceanic was one of the rescue vessels that retrieved bodies from the sinking of the RMS Titanic in 1912.|
|Olympic||Sunk U-103 on 12 May 1918, the only known incident in World War I in which a merchant vessel sank an enemy warship.|
|Ophir||Converted to Hospital Ship in 1918. Returned to the owners in 1919 but never refitted, being broken up in 1922.|
|Orama||Lost on 19 October 1917.|
|Orbita||Also served in the Second World War as a troop carrier from 1941 to 1946.|
|Oropesa||Transferred to France as Champagne on 2 December 1915. Renamed as Oropesa in July 1917.|
|Otranto||Survived the Battle of Coronel, stranded on Islay after a collision with the steamship SS Kashmir on 6 October 1918.|
|Otway||Lost on 23 July 1917 torpedoed by German submarine UC 49.|
|Patia||Lost on 13 June 1918.|
|Princess||Ex-Kronprincess Cecilie; Acted as dummy battleship HMS Ajax.|
|Teutonic||Commissioned into the 10th Cruiser Squadron. In 1916, she was refitted with 6-inch guns, and served as a convoy escort ship as well as being used for troop transport.|
|Viknor||Ex-RMS Atrato (1888–1912), RMS Viking (1912–1914). Lost on 13 January 1915 off Tory Island.|
|Berrima||Became Troop Carrier, October 1914.|
|Artois||Ex-Royal Navy Digby.|
|Champagne||Ex-Royal Navy Oropesa, lost on 9 October 1917.|
German auxiliary cruisers
|Cap Trafalgar||Used the alias Carmania; Cap Trafalgar was sunk by RMS Carmania which used the alias Cap Trafalgar.|
|Iltis x Turritella x Gutenfels|
|Kaiser Wilhelm der Grosse|
|Prinz Eitel Friedrich|
|Victoria Luise x Deutschland|
|Wolf x Belgravia|
|Wolf x Wachtfeld|
Spanish Civil War
|Mar Cantábrico||Formerly under Republican control, she was captured by the Nationalist cruiser Canarias on 8 March 1937 off Santander. Assisted by the minelayer Vulcano, she took the largest foreign prize of the war with the capture of the Greek steamer Victoria, of 6,600 long tons (6,700 t), on 16 May 1938.|
|Mar Negro||Under Republican flag at the beginning of the war, her captain and crew changed loyalties off Bone, Algeria, while returning to Barcelona from the Soviet Union. She seized the last cargo ship captured during the civil war, the British Stangate off Valencia on 16 March 1939, despite the opposition of HMS Sussex.|
|Ciudad de Valencia||She used the alias Nadir for operations in the North Sea. She sank the Republican merchantman SS Cantabria off Cromer, Norfolk, on 2 November 1938. The Republican steamers Josiña and Guernica were forced to seek shelter in Norwegian and Swedish waters, where the latter ran aground on 19 November at the island of Nidingen, in the Kattegat. Josiña reached Kristiansand, and she remained interned there until 1939.|
|Ciudad de Alicante||She supported the Ciudad de Valencia in the North Sea, where she played a secondary role in the capture of the Republican steamers Sil and Río Miera. Ciudad de Alicante and Ciudad de Valencia used the German port of Lunden as a resupply base.|
|Ciudad de Palma||Converted to a warship in Italy in 1936. She assisted the minelayer Júpiter in the capture of the British cargo ship Candlestone Castle in Biscay on 17 July 1937.|
|Ciudad de Mahón|
|Vicente Puchol||After an initial deployment as an improvised minelayer, she was later converted to an auxiliary cruiser. She seized the 1,743 ton freighter Pomaron on 21 February 1938. The ship was the property of Strubin & Co. of London, and was sailing under Estonian flag. She was confiscated and placed under Spanish flag as Castillo Butrón.|
|Antonio Lázaro||After an initial deployment as an improvised minelayer, she was later converted to an auxiliary cruiser. The British liner Llandovery Castle was badly damaged when she struck a mine laid by Lázaro off Cap de Creus on 25 February 1937.|
|Domine||Active as auxiliary cruiser in the bay of Biscay from September to December 1936. Converted into a fast transport to carry allied moor pilgrims to Mecca in January 1937, she was later deployed in the Mediterranean as supply ship.|
|Italian Barletta||Renamed Rio during operations in the Spanish war. She captured the Greek tanker Burlington (under British flag) in the central Mediterranean in 1937. Attacked in Palma de Mallorca by Republican bombers on 26 May 1937. After carrying out four missions, she was disarmed and used as supply ship by Nationalist forces before being returned to Italy. She saw service also during WWII under Italian flag.|
|Italian Adriatico||Renamed Lago during operations in the Spanish war. After three unsuccessful missions, she was disarmed and used as supply ship by Nationalist forces before being returned to Italy. She saw service also during WWII under Italian flag. Sunk by light cruiser HMS Aurora off Cape Bon on 1 December 1941.|
World War II
Allied merchant cruisers
The Armed merchant cruisers were made by requisitioning large ships and providing them with guns and other equipment. They ranged from 6,000–22,000 long tons (6,100–22,400 t). The armament varied but six 6 in (150 mm) guns with 3 in (76 mm) guns as secondary was usual. From 1941, many served as troopships.
|Andania||Lost, 16 June 1940, sunk by German submarine U-A.|
|Carinthia||Lost, 6 June 1940, sunk by U-46 west of Ireland.|
|Casanare||Sunk 3 November 1940 along with HMS Patroclus and HMS Laurentic by U-99.|
|Comorin||Lost on 6 April 1941. Her burnt out wreck was sunk by HMS Broke.|
|Duchess of Richmond|
|Duchess of York|
|Dunvegan Castle||Lost on 27 August 1940, sunk by U-46 west of Ireland.|
|Empress of Asia||Lost on 5 February 1942.|
|Empress of Australia|
|Empress of Britain||Lost on 28 October 1940.|
|Empress of Canada|
|Empress of Japan|
|Empress of Russia|
|Empress of Scotland|
|Forfar||sunk by U-99 on 2 December 1940.|
|Hector||Was decommissioned when lost on 5 April 1942 during the Japanese Indian Ocean raid.|
|Jervis Bay||Lost on 5 November 1940 in an engagement against the German cruiser Admiral Scheer. Her commander, Captain Fegen, was awarded a posthumous Victoria Cross.|
|Kanimbla||Transferred to the Royal Australian Navy as a Landing Ship Infantry in 1943|
|Laurentic||Lost on 3 November 1940, sunk by U-99 west of Ireland.|
|Patroclus||Lost on 4 November 1940, sunk by U-99 west of Ireland.|
|Pretoria Castle||Converted into an escort carrier as HMS Pretoria Castle.|
|Queen of Bermuda|
|Rajputana||Lost on 13 April 1941, sunk by U-108 west of Ireland.|
|Rawalpindi||Lost on 23 November 1939, sunk by Scharnhorst and Gneisenau. Her commander, Captain Edward Coverley Kennedy, was posthumously Mentioned in Dispatches.|
|Salopian||Lost on 13 May 1941, sunk by U-98, North Atlantic.|
|Scotstoun||Lost on 13 June 1940, sunk by U-25 north-west of Ireland.|
|Transylvania||Lost on 10 August 1940, sunk by U-56 north-west of Malin Head.|
|Voltaire||Lost on 4 April 1941, sunk by German auxiliary cruiser Thor.|
|Worcestershire||Damaged by U-74 on 3 April 1941|
French auxiliary cruisers were armed with 138 mm, 152 mm or 150 mm guns, 75 mm and 37 mm AA guns and 13.2 mm or 8 mm AA HMG
- Aramis (X01)
- Ville D'Alger (X03)
- Cap des Palmes (X03)
- Ville d'Oran (X05)
- El Mansour (X06)
- Victor Scoelcher (X07) (lost on 6 May 1942)
- Colombie (X10)
- Charles Plumier (X11)
- Djenné (X13)
- El Kantara (X16)
- El Djezair (X17)
- Eridan (X18)
- Barfleur (X19)
- Quercy (X20)
- Esterel (X21)
- Mexique (X22) (hit a mine and sunk on 19 June 1940)
German auxiliary cruiser raiders
At the outbreak of war, the German Navy (Kriegsmarine) requisitioned a number of fast merchantmen and immediately sent them into naval shipyards to be converted into offensive auxiliary cruisers. These ships had at the time of building been fitted with extra strong decks specifically to facilitate the installation of military equipment when required, but this was the only difference between them and other merchantmen of the period. No precise plans had been drawn up for the conversion of these ships into warships, and consequently the conversion process was painfully long. Compared to the diversity of British auxiliary cruisers, the Hilfskreuzer were standardized insofar as possible. The ships themselves averaged approximately 7,000 long tons (7,100 t). Armament usually consisted of six 6 in guns, two to six torpedo tubes, and an assortment of 40 mm (1.57 in), 37 mm, and 20 mm (0.79 in) automatic weapons. Most of these merchant raiders carried an Arado Ar 196 floatplane for reconnaissance. Kormoran, Komet, and Michel were also equipped with small motor torpedo boats. In addition to armament, increased fuel, water, and coal storage had to be provided for as well. Furthermore, the raiders could not abandon the crews of their captures, so space had to be provided for prisoners. The first Hilfskreuzer got under way in March 1940, shortly before the Norwegian campaign.
- Orion (HSK-1)
- Atlantis (HSK-2)
- Widder (HSK-3)
- Thor (HSK-4)
- Pinguin (HSK-5)
- Stier (HSK-6)
- Komet (HSK-7)
- Kormoran (HSK-8)
- Michel (HSK-9)
- Coronel (HSK-10)
- Hansa (HSK-11)
Japanese armed merchant cruisers
Japan converted fourteen merchant ships to "armed merchant cruisers" but, by the end of 1943, five had been sunk and seven had been converted back to merchant ships.
- Aikoku Maru
- Akagi Maru
- Asaka Maru
- Awata Maru
- Bangkok Maru
- Gokoku Maru
- Hokoku Maru
- Kinryu Maru
- Kiyozumi Maru
- Kongō Maru
- Noshiro Maru
- Saigon Maru
- Ukishima Maru
Italian armed merchant cruisers
Unlike the Germans and the Japanese, none of the armed merchant cruisers (or auxiliary cruisers) of the Italian Royal Navy (Regia Marina) were deployed to destroy or capture Allied merchant ships. All of them mounted two 4.7 in (120 mm) guns.
- Ramb I - Lost on 27 February 1941 in battle with cruiser HMNZS Leander in the Indian Ocean.
- Ramb II - Never active as an Italian armed merchant cruiser and, after being chartered by the Japanese as the Calitea II, lost on 12 January 1945
- Ramb III - Converted into an escort vessel and never served as an armed merchant cruiser, she took part of the battle of Otranto
- Ramb IV - Converted into a hospital ship and never served as an armed merchant cruiser
Despite a rise in modern piracy, it is very unusual for modern merchant ships to be armed, save for maybe a number of small arms and the use of the ship's fire hoses to repel boarders. One exception to this are the ships of Pacific Nuclear Transport Limited, which are used to transport spent nuclear fuel and reprocessed uranium on behalf of BNFL. Transporting enough fissile material between them to produce 50-60 nuclear weapons, these ships—beginning with the Pacific Pintail and Pacific Teal—became armed in 1999 to avoid the cost of a Royal Navy escort. Travelling together in convoy during these ships intermittent voyages, they have an onboard escort of armed police from the UKAEAC and its successors  and are equipped with two or three 30 mm (1.18 in) autocannons.
In April 2010, it was reported that a Russian company is offering a version of the 3M-54 Klub missile that can be disguised and launched from a shipping container, in theory enabling any cargo ship to be armed with an anti-ship missile. This type of missile is allegedly capable of disabling or even sinking an aircraft carrier, but "...it's not known how many of them..."
During the 2011 Libyan civil war, forces loyal to Gaddafi armed several merchant vessels and attempted to use them to blockade the port of Misrata.
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