An armed merchantman is 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.
SS Alcantara was an ocean liner which entered service just weeks before the start of World War I, was converted to an armed merchant cruiser in 1915, and was sunk in combat with the German armed merchant cruiser SMS Greif in the Action of 29 February 1916.
RMS Alcantara was a Royal Mail Lines ocean liner that was built in Belfast in 1926. She served in the Second World War first as an armed merchant cruiser and then a troop ship. She returned to civilian service in 1948 and was scrapped in 1958.
Orion (HSK-1) was an auxiliary cruiser of Nazi Germany's Kriegsmarine which operated as a merchant raider in World War II. Blohm & Voss built her in Hamburg in 1930–31 as the cargo ship Kurmark. The navy requisitioned her at the start of World War II, had her converted into the auxiliary cruiser Orion, and commissioned her on 9 December 1939. Known to the Kriegsmarine as Schiff 36, her Royal Navy designation was Raider A. She was named after the constellation Orion.
Widder was an auxiliary cruiser (Hilfskreuzer) of Nazi Germany's Kriegsmarine that was used as a merchant raider in the Second World War. Her Kriegsmarine designation was Schiff 21, to the Royal Navy she was Raider D. The name Widder (Ram) represents the constellation Aries in German.
Stier was an auxiliary cruiser of Nazi Germany's Kriegsmarine during World War II. Her Kriegsmarine designation was Schiff 23, to the Royal Navy she was Raider J.
SMS Wolf was an armed merchant raider or auxiliary cruiser of the Imperial German Navy in World War I. She was the fourth ship of the Imperial Navy bearing this name, following two gunboats and another auxiliary cruiser that was decommissioned without seeing action.
SS Cap Trafalgar was a German ocean liner launched in 1913 for the Hamburg Süd line. In 1914, she was converted for use as an auxiliary cruiser during World War I. She was the first armed merchant cruiser sunk by a ship of the same class; she was destroyed by HMS Carmania, also a converted ocean liner, in a furious action in the South Atlantic in September 1914. It was the world's first battle between former ocean liners.
Michel(HSK-9) was an auxiliary cruiser of Nazi Germany's Kriegsmarine that operated as a merchant raider during World War II. Built by Danziger Werft in Danzig 1938/39 as the freighter Bielsko for the Polish Gdynia-America-Line (GAL), she was requisitioned by the Kriegsmarine at the outbreak of World War II and converted into the hospital ship Bonn. In the summer of 1941, she was converted into the auxiliary cruiser Michel, and was commissioned on 7 September 1941. Known as Schiff 28, her Royal Navy designation was Raider H. She was the last operative German raider of World War II.
SMS Möwe was a merchant raider of the Imperial German Navy which operated against Allied shipping during World War I.
The Action of 16 March 1917 was a naval engagement in which the British armed boarding steamer SS Dundee and HMS Achilles, a Warrior-class armoured cruiser, fought the German auxiliary cruiser SMS Leopard, which sank with the loss of all 319 hands and six men of a British boarding party.
SS Dundee was a British steamship that was built in Scotland in 1911 and sunk by enemy action in the Celtic Sea in 1917. She was designed as a coastal passenger and cargo liner for the Dundee, Perth & London Shipping Company Ltd, but in 1915 she was converted into an armed boarding steamer for the Royal Navy. She took part in the Action of 16 March 1917, was sunk by a U-boat six months later, and lost members of her crew in both actions.
SM U-70 was a Type U 66 submarine or U-boat for the German Imperial Navy during the First World War. She had been laid down in February 1914 as U-11 the final boat of the U-7 class for the Austro-Hungarian Navy but was sold to Germany, along with the others in her class, in November 1914.
Vice-Admiral Thomas Erskine Wardle, was a senior officer in the Royal Navy. He was the Rear-Admiral Commanding His Majesty's Australian Fleet from 30 April 1924 to 30 April 1926.
The action of 29 February 1916 was a naval engagement fought during the First World War between the United Kingdom and the German Empire. SMS Greif, a German commerce raider, broke out into the North Sea and Admiral Sir John Jellicoe dispatched Royal Navy warships to intercept the raider. Four British vessels intercepted the commerce raider Greif. The armed merchant cruiser RMS Alcantara and Greif fought a brief engagement before British reinforcements arrived when both were severely damaged, both being sunk.
SMS Leopard was a British cargo steamship that was built in 1912 as Yarrowdale, captured in 1916 by the Imperial German Navy, converted into a commerce raider in Germany, and sunk with all hands by the Royal Navy in 1917.
SMS Meteor was an auxiliary cruiser of the Imperial German Navy which operated against Allied shipping during World War I.
The German commerce raiders of World War I were surface vessels used by the Imperial German Navy for its Handelskrieg, a campaign against Allied seaborne trade. The ships comprised warships, principally cruisers, stationed in the German colonial empire before the war began, express liners commissioned as auxiliary cruisers and later, freighters outfitted as merchant raiders. These vessels had a number of successes and had a significant effect on Allied naval strategy, particularly in the early months of the war.
SS Cap Polonio was a German 20,576 GRT ocean liner that was launched in 1914 and scrapped in 1935. She worked the Hamburg Südamerikanische Dampfschifffahrtsgesellschaft route between Hamburg in Germany and Buenos Aires in Argentina. She was named after Cabo Polonio in Uruguay.
SMS Emden was the second and final member of the Dresden class of light cruisers built for the Imperial German Navy. Named for the town of Emden, she was laid down at the Kaiserliche Werft in Danzig in 1906. The hull was launched in May 1908, and completed in July 1909. She had one sister ship, Dresden. Like the preceding Königsberg-class cruisers, Emden was armed with ten 10.5 cm (4.1 in) guns and two torpedo tubes.
Germany 
