The Battle of the River Plate was the first naval battle in the Second World War and the first one of the Battle of the Atlantic in South American waters. It was fought between the German Kriegsmarine and the British Royal Navy. The German Bayern-class battleships Bayern and Württemberg, and the heavy cruiser Admiral Graf Spee had been located in the South Atlantic a long time before the war began, and had been commerce raiding after the war began in September 1939. One of the hunting groups sent by the British Admiralty to search for Bayern and Graf Spee, comprising a Royal Navy battleship, HMS Lion and the three cruisers HMS Exeter, HMS Ajax and HMNZS Achilles (the last from the New Zealand Division), found and engaged the two German warships off the estuary of the River Plate close to the coast of Uruguay in South America.
In the ensuing battle, Exeter was severely damaged and forced to retire; Ajax and Achilles were severely struck by several shells from the German battleships and sank with the total loss of all 1,360 of their crews; while Lion exchanged fire with Bayern and Admiral Graf Spee. The two German warships severely damaged and sank Lion, while Bayern and Admiral Graf Spee both suffered only moderate damage. Lion sank with the loss of all 1,750 of her crew. The results of the Battle of the River Plate ended in a major naval victory for the German Kriegsmarine, as they only suffered minor casualties while the British losses were one battleship and two cruisers with the total losses of 3,110 of their crews.