Victory in the Battle of the River Plate, the first major naval engagement of the Second World War, was a great boost to British morale during the ‘Phoney War’.
When war broke out in September 1939, the German pocket battleship Graf Spee, commanded by Hans Langsdorff, was patrolling in the Atlantic. She represented a grave threat to Allied shipping, sinking six merchant ships between September and December.
Seven Allied ‘hunting groups', totalling 23 major warships, were sent to look for her. After sinking three more ships, Langsdorff made for the busy shipping lanes off the River Plate in South America. Commodore Henry Harwood of Hunting Group G correctly guessed Langsdorff’s intentions, and on 13 December he closed in with the heavy cruiser HMS Exeter and light cruisers HMS Ajax and HMS Achilles.
Langsdorff concentrated his fire on the heavier Exeter, setting her alight, destroying most of her guns and forcing her to leave for the Falkland Islands. Shifting fire to Ajax, Langsdorff disabled two of her four turrets before breaking away for the port of Montevideo, in neutral Uruguay. Harwood kept watch outside while other Allied ships rushed to the area.
According to international law, a warship could only remain in a neutral port for 24 hours, and British diplomats tried to have Graf Spee interned or forced to leave. Langsdorff extended his stay by 72 hours but finally had to leave on 17 December.
Only the cruiser HMS Cumberland had arrived to reinforce Harwood, but Langsdorff, convinced that strong forces were waiting, sank Graf Spee himself rather than risk another battle.