In both World Wars, both
Germany and the
United Kingdom used auxiliary cruisers. While 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 , 14 September 1914 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
ocean 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 AMCs. The downside proved to be their high fuel consumption; 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. A famous AMC of World War I was the British which, after a battle that caused heavy damage on both sides, sank the German auxiliary cruiser near the Brazilian island of
Trindade in 1914. By coincidence,
Cap Trafalgar was disguised as
Carmania. In World War II, , the sole escort for
convoy HX 84 in November 1940, stood off the
pocket battleship , when the German ship attacked the convoy. Though she and five vessels of the convoy were sunk, this enabled the rest of the convoy to escape. Her master, Acting Captain
Edward Fegen was awarded the
Victoria Cross posthumously for his actions. Another famous action involving an armed merchant cruiser was the November 1939 battle between and the German
battlecruisers and . Outgunned, the
Rawalpindi was quickly sunk.
Auxiliary cruisers The
Spanish and
United States Navies 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 scheme. 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 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. was a former passenger liner that sank two freighters in 1914 before being caught by . Her sister ship, , 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 , a sailing ship under the command of the legendary Count
Felix von Luckner. However, both and were each much more successful than
Seeadler. In World War II, Nazi Germany's
Kriegsmarine operated ten very successful auxiliary cruisers, ranging in tonnage from 3,860 to 9,400; typically these vessels were equipped with: •
Observation seaplanes • 15 cm (6 in) guns • Smaller armaments (typically hidden away behind specially designed and hinged bulwarks, or beneath fake deckhouses and/or skylights) •
Torpedoes •
Mines To preserve their cover, these ships flew the flags of neutral or occasionally Allied nations. They were refueled and provisioned from special supply ships, from Japanese island bases or from
prizes they had taken. To counter the effectiveness of these disguises, the Allies introduced the
check-mate system in 1942 to identify individual ships on a one-by-one basis with the
Admiralty in London. on
19 November 1941, off the coast of Western Australia the German auxiliary cruiser
Kormoran sank before being scuttled. In one incident, the German (ex-merchantman
Steiermark) managed to surprise and sink the Australian
light cruiser , which approached too close, though
Kormoran 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.
Kormorans attack upon
Sydney was motivated by desperation. She was not the most successful German raider of World War II (both and scored higher kill tonnages). Another, , was also sunk in a mutually destructive engagement with the American
Liberty ship . The only encounters between Allied and Axis auxiliary cruisers in World War II were all with the raider . This small vessel, which captured or sank 22 merchantmen, encountered three British AMCs in her career, defeating and and later sinking HMS
Voltaire in the
Action of 4 April 1941. During World War II, German auxiliary cruisers are believed to have either sunk or captured some of Allied shipping.
Others 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. CAM and MAC ships remained as civilian ships operated by civilian crews, with
Fleet Air Arm or
Royal Netherlands Navy "air parties". == Cold War and 21st century ==