Battle of The River Plate - Background

Background

Admiral Graf Spee had been at sea at the start of the Second World War in September 1939, and had sunk several merchantmen in the Indian Ocean and South Atlantic Ocean without loss of life, due to her captain's policy of taking all crews on board before sinking the victim.

The Royal Navy assembled nine forces to search for the surface raider. Force G—the South American Cruiser Squadron—comprised the heavy cruiser HMS Exeter of 8,390 long tons (8,520 t) with six 8 in (200 mm) guns in three turrets, and two Leander-class light cruisers, both of 7,270 long tons (7,390 t) with eight 6 in (150 mm) guns—HMS Ajax and Achilles. Although technically a heavy cruiser because of the calibre of her guns, Exeter was a scaled-down version of the County class, which had eight 8 in (200 mm) guns. The force was commanded by Commodore Henry Harwood from Ajax, which was captained by Charles Woodhouse. Achilles was of the New Zealand Division (precursor to the Royal New Zealand Navy) and captained by Edward Parry. F. S. Bell commanded Exeter. A County-class heavy cruiser—HMS Cumberland of 10,000 long tons (10,160 t)—was refitting in the Falkland Islands at the time, but was available at short notice.

Following a raider-warning radio message from the merchantman Doric Star, which was sunk by Graf Spee off South Africa, Harwood suspected that the raider would try to strike next at the merchant shipping off the River Plate estuary between Uruguay and Argentina. He ordered his squadron to steam toward the position 32° south, 47° west. Harwood chose this position, according to his despatch, due to its being the most congested part of the shipping routes in the South Atlantic, and therefore the point where a raider could do the most damage to enemy shipping. A Norwegian freighter saw Graf Spee practising the use of its searchlights and radioed its course toward South America.

The three cruisers rendezvoused off the estuary on 12 December and conducted manoeuvres. Harwood's combat policy of three cruisers versus one pocket battleship was to attack at once, day or night. If during the day, the ships would attack as two units, with Exeter separate from Ajax and Achilles. If at night, the ships would remain in company, but in open order. By attacking from two sides, Harwood hoped to give his lighter warships a chance of overcoming the German advantage of greater range and heavier broadside by dividing the enemy's fire.

Although outgunned by Graf Spee and therefore at a tactical disadvantage, the British did have the upper hand strategically. Any raider returning to Germany would have to run the blockade of the North Sea, and it might be reasonably expected that an engagement would therefore take place with the Home Fleet. For victory, the British only had to damage the raider enough so that she was unable to make either the journey and/or unable to fight the subsequent battle with the Home Fleet (by contrast the Germans would have to destroy the Allied force without being severely damaged themselves). Furthermore, because of overwhelming numerical superiority, the loss of even all three cruisers would not have severely dented Allied naval capabilities, whereas Graf Spee was one of the Kriegsmarine′s few capital ships. The British could afford to risk a tactical defeat if it brought overall strategic victory.