High Quality Content by WIKIPEDIA articles! The Battle of the River Plate was the first naval battle in the Second World War and the only episode of the war to take place in South America. The German pocket battleship Admiral Graf Spee had been commerce raiding since the start of the war in September 1939. One of the hunting groups sent by the British Admiralty to search for Graf Spee, comprising three Royal Navy (RN) cruisers, HMS Exeter, Ajax and Achilles (the last of the New Zealand Division), found and engaged their quarry off the estuary of the River Plate close to the coast of Argentina and Uruguay in South America.