The Battle of the River Plate was fought in the South Atlantic on 13 December 1939 as the first naval battle of the Second World War. The Kriegsmarine heavy cruiser Admiral Graf Spee, commanded by Captain Hans Langsdorff, engaged a Royal Navy squadron, commanded by Commodore Henry Harwood, comprising the light cruisers HMS Ajax, HMS Achilles and the heavy cruiser HMS Exeter.
The German auxiliary cruiser Atlantis, known to the Kriegsmarine as Schiff 16 and to the Royal Navy as Raider-C, was a converted German Hilfskreuzer, or merchant or commerce raider of the Kriegsmarine, which, in World War II, travelled more than 161,000 km (100,000 mi) in 602 days, and sank or captured 22 ships with a combined tonnage of 144,384. Atlantis was commanded by Kapitän zur See Bernhard Rogge, who received the Oak Leaves to the Knight's Cross of the Iron Cross. She was sunk on 22 November 1941 by the British cruiser HMS Devonshire.
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.
The Leander class was a class of eight light cruisers built for the Royal Navy in the early 1930s that saw service in World War II. They were named after mythological figures, and all ships were commissioned between 1933 and 1936. The three ships of the second group were sold to the Royal Australian Navy (RAN) before World War II and renamed after Australian cities.
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.
SMS Möwe was a merchant raider of the Imperial German Navy which operated against Allied shipping during World War I.
HMS Achilles was a Warrior-class armoured cruiser built for the Royal Navy in the first decade of the 20th century. She served with the 2nd Cruiser Squadron for most of the First World War. The ship did not participate in the Battle of Jutland in 1916, but did sink the German raider Leopard in 1917. Achilles became a training ship in 1918 and was sold for scrap in 1921.
HMS Turbulent (N98) was a T-class submarine of the Royal Navy. It was laid down by Vickers Armstrong, Barrow and launched in May 1941.
HMS Hector was a UK steam turbine passenger and refrigerated cargo liner launched in 1924. She was the fourth of six civilian ships to bear the name.
SS Manistee was an Elders & Fyffes Ltd banana boat that was launched in 1920. She was one of a numerous class of similar banana boats built for Elders & Fyffes in the 1920s.
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.
HMS Baralong was a cargo steamship that was built in England in 1901, served in the Royal Navy as a Q-ship in the First World War, was sold into Japanese civilian service in 1922 and scrapped in 1933. She was renamed HMS Wyandra in 1915, Manica in 1916, Kyokuto Maru in 1922 and Shinsei Maru No. 1 in 1925.
SM U-21 was a U-boat built for the Imperial German Navy shortly before World War I. The third of four Type U-19-class submarines, these were the first U-boats in German service to be equipped with diesel engines. U-21 was built between 1911 and October 1913 at the Kaiserliche Werft in Danzig. She was armed with four torpedo tubes and a single deck gun; a second gun was added during her career.
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.
An armed boarding steamer was a merchantman that the British Royal Navy converted to a warship during the First World War. AB steamers or vessels had the role of enforcing wartime blockades by intercepting and boarding foreign vessels. The boarding party would inspect the foreign ship to determine whether to detain the ship and send it into port or permit it to go on its way.
Admiral Graf Spee was a Deutschland-class "Panzerschiff", nicknamed a "pocket battleship" by the British, which served with the Kriegsmarine of Nazi Germany during World War II. The vessel was named after World War I Admiral Maximilian von Spee, commander of the East Asia Squadron who fought the battles of Coronel and the Falkland Islands, where he was killed in action. She was laid down at the Reichsmarinewerft shipyard in Wilhelmshaven in October 1932 and completed by January 1936. The ship was nominally under the 10,000 long tons (10,160 t) limitation on warship size imposed by the Treaty of Versailles, though with a full load displacement of 16,020 long tons (16,280 t), she significantly exceeded it. Armed with six 28 cm (11 in) guns in two triple gun turrets, Admiral Graf Spee and her sisters were designed to outgun any cruiser fast enough to catch them. Their top speed of 28 knots left only a few capital ships in the Anglo-French navies fast enough and powerful enough to sink them.
TSS (RMS) King Orry (III) – the third ship in the history of the Company to bear the name – was a passenger steamer which served with the Isle of Man Steam Packet Company, until she was sunk in the evacuation of Dunkirk in 1940.
HMS Perth was a steamship that was built in Scotland in 1915, renamed Lafonia in 1946 and Valfiorita in 1950, and scrapped in Italy in 1962. She was designed as a coastal passenger and cargo liner, but was completed in the First World War as an armed boarding steamer for the Royal Navy. In the Second World War she was converted into an ocean boarding vessel, and served also as a convoy rescue ship.
The Warrior class consisted of four armoured cruisers built for the Royal Navy in the first decade of the 20th century. After commissioning, all four sister ships were assigned to the Channel and Home Fleets until 1913 when Warrior was transferred to the Mediterranean Fleet. After the start of World War I in August 1914, Warrior participated in the pursuit of the German battlecruiser SMS Goeben and light cruiser SMS Breslau and her three sisters were assigned to the 2nd Cruiser Squadron of the Grand Fleet. Warrior joined the 1st Cruiser Squadron of the Grand Fleet in late 1914. Neither squadron participated in any of the naval battles in the North Sea in 1915. Natal was destroyed by a magazine explosion in late 1915 and only two of the ships participated in the Battle of Jutland in 1916. Cochrane was not engaged during the battle, but Warrior was heavily damaged and sank the following morning.
Royal Navy 
Dundee 
