The Battle of the River Plate is fought off the coast of Uruguay; the first naval battle of World War II. The Kriegsmarine's Deutschland-class cruiser (pocket battleship) Admiral Graf Spee engages with three Royal Navy cruisers: HMS Ajax, HMNZS Achilles and HMS Exeter.

The Battle of the River Plate was fought in the South Atlantic on 13 December 1939 as the first British naval battle of the Second World War.

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

The Kriegsmarine was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war Reichsmarine (1919–1935) of the Weimar Republic. The Kriegsmarine was one of three official branches, along with the Heer and the Luftwaffe, of the Wehrmacht, the German armed forces from 1935 to 1945.

The Deutschland class was a series of three Panzerschiffe, a form of heavily armed cruiser, built by the Reichsmarine officially in accordance with restrictions imposed by the Treaty of Versailles. The ships of the class, Deutschland, Admiral Scheer, and Admiral Graf Spee, were all stated to displace 10,000 long tons (10,160 t) in accordance with the Treaty, though they actually displaced 10,600 to 12,340 long tons at standard displacement. The design for the ships incorporated several radical innovations, including the first major use of welding in a warship and all-diesel propulsion. Due to their heavy armament of six 28 cm (11 in) guns and lighter weight, the British began referring to the vessels as "pocket battleships". The Deutschland-class ships were initially classified as Panzerschiffe, but the Kriegsmarine reclassified them as heavy cruisers in February 1940.