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.
The Kriegsmarine heavy cruiser Admiral Graf Spee, commanded by Captain Hans Langsdorff, engaged a Royal Navy squadron, commanded by Commodore Henry Harwood, comprising the light cruisers HMS Ajax, HMNZS Achilles (on loan to the New Zealand Division) and the heavy cruiser HMS Exeter.
Graf Spee had sailed into the South Atlantic in August 1939, before the war began, and had begun commerce raiding after receiving authorisation on 26 September 1939. Harwood's squadron was one of several search groups sent in pursuit by the British Admiralty and sighted Graf Spee off the estuary of the River Plate (a.k.a. the Río de la Plata) near the coasts of Argentina and Uruguay.
In the ensuing battle, Exeter was severely damaged and forced to retire, making for the Falklands; Ajax and Achilles suffered moderate damage. Damage to Graf Spee, although not extensive, was critical because her fuel system was crippled. Ajax and Achilles shadowed the German ship until she entered the port of Montevideo, the capital of neutral Uruguay, to effect urgent repairs. Langsdorff was told that his stay could not be extended beyond 72 hours. Apparently believing that the British had gathered a superior force to await his departure, he ordered for the ship to be scuttled on 17 December. Langsdorff died by suicide two days later.
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 because of 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 County-class heavy cruiser HMS Cumberland of 10,570 long tons (10,740 t) with eight 8-inch (203 mm) guns in four turrets, the York-class heavy cruiser HMS Exeter of 8,390 long tons (8,520 t) with six 8-inch (203 mm) guns in three turrets, and two Leander-class light cruisers, HMS Ajax and HMNZS Achilles, both of 7,270 long tons (7,390 t) with eight 6-inch (150 mm) guns. Although technically a heavy cruiser because of the calibre of her guns, Exeter was a scaled-down version of the County class. The force was commanded by Commodore Henry Harwood whose flagship was Ajax, captained by Charles Woodhouse. Achilles was on loan to the New Zealand Division (precursor to the Royal New Zealand Navy) and captained by Edward Parry. Exeter was commanded by Captain Frederick Secker Bell.
At the time of the battle, Cumberland (commanded by Captain Walter Herman Gordon Fallowfield) was refitting in the Falkland Islands but was available for sea at short notice. Force G was supported by the oilers RFA Olna, RFA Olynthus, and RFA Orangeleaf. Olynthus replenished HMS Ajax and Achilles on 22 November 1939, and Exeter on 26 November, at San Borombon Bay. Olynthus was also directed to keep observation between Medanos and Cape San Antonio, off Argentina south of the River Plate estuary (see chart below).
Following a raider-warning radio message from the merchantman Doric Star, which was sunk by Admiral 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 that position, according to his dispatch, because it was the most congested part of the shipping routes in the South Atlantic and therefore the point at which a raider could do the most damage to enemy shipping. A Norwegian freighter saw Admiral Graf Spee practising the use of her searchlights and radioed that her course was toward South America; the three available cruisers of Force G rendezvoused off the estuary on 12 December and conducted manoeuvres.
Regarding strategy, the British combat instructions for engaging a pocket battleship with a cruiser squadron had been devised by Harwood himself during his period at the Royal Naval War College between 1934 and 1936. The strategy specified an attack at once, day or night. During the day, the ships would attack as two units, in this case with Exeter separate from Ajax and Achilles. 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. By splitting his force, Harwood would force the Germans to split their fire and reduce its effectiveness, or to keep it focused on one opponent and allow the other vessels to attack with less fear of return fire.
Although outgunned by Admiral Graf Spee and therefore at a tactical disadvantage, the British had the upper hand strategically since any raider returning to Germany would have to run the blockade of the North Sea and might reasonably be expected to encounter the Home Fleet. For victory, the British had only to damage the raider enough so that she was either unable to make the journey or unable to fight a subsequent battle with the Home Fleet (by contrast, the Germans would have to destroy the British force without being severely damaged). Because of overwhelming numerical superiority, the loss of even all three cruisers would not have severely altered Britain's naval capabilities, but Admiral Graf Spee was one of the Kriegsmarine's few capital ships. The British could, therefore, afford to risk a tactical defeat if it brought strategic victory.
Battle
On 13 December at 05:20, the British squadron was proceeding on a course of 060° at 14 knots with Ajax at 34°34′S 48°17′W / 34.567°S 48.283°W, 390 nmi (720 km) east of Montevideo. At 06:10, smoke was sighted on a bearing of Red-100, or 320° (to the north-west). Harwood ordered the Exeter to investigate. She swung out of line, and at 06:16, she signaled by lamp: "I think it is a pocket-battleship". Captain Bell ordered Flag N hoisted to the yard arm – "Enemy in sight". Graf Spee had already sighted mastheads and identified Exeter but initially suspected that the two light cruisers were smaller destroyers and that the British ships were protecting a merchant convoy, the destruction of which would be a major prize. Since Graf Spee's reconnaissance aircraft was out of service, Langsdorff relied on his lookouts for that information. He decided to engage despite having received a broadly accurate report from the German naval staff on 4 December. It outlined British activity in the River Plate area and included information that Ajax, Achilles, Cumberland and Exeter were patrolling the South American coast.
Langsdorff realised too late that he was facing three cruisers. Calling on the immediate acceleration of his diesel engines, he closed with the enemy squadron at 24 kn (28 mph; 44 km/h) in the hope of engaging the steam-driven British ships before they could work up from cruising speed to full power. An alternative strategy would have been keeping the British ships at a distance to destroy them with his 283 mm (11.1 in) guns and remaining out of range of their smaller 6-inch and 8-inch guns. However, Langsdorff knew the British cruisers had a 4–6 kn (4.6–6.9 mph; 7.4–11.1 km/h) speed advantage over Graf Spee and could stay out of range while calling for reinforcements.
The British executed their battle plan: Exeter turned north-west, and Ajax and Achilles, operating together, turned north-east to spread Graf Spee's fire. Graf Spee opened fire on Exeter at 19,000 yd (17,000 m) with her six 283 mm (11.1 in) guns at 06:18. Exeter opened fire at 06:20, Achilles at 06:21, Exeter's aft guns at 06:22 and Ajax at 06:23. Lieutenant-Commander Richard Jennings, Exeter's gunnery officer remembers:
As I was crossing the compass platform [to his Action Station in the Director Control Tower], the captain hailed me, not with the usual rigmarole of "Enemy in sight, bearing, etc", but with "There's the fucking Scheer! Open fire at her!" Throughout the battle the crew of the Exeter thought they were fighting the [sister ship] Scheer. But the name of the enemy ship was of course the Graf Spee.
From her opening salvo, Graf Spee's gunfire proved fairly accurate, her third salvo straddling Exeter. At 06:23, a 283 mm (11.1 in) shell burst just short of Exeter, abreast the ship. Splinters from the shell killed the torpedo tubes' crews, damaged the ship's communications, riddled the ship's funnels and searchlights and wrecked the ship's Walrus aircraft just as it was about to be launched for gunnery spotting. Three minutes later, Exeter suffered a direct hit on her "B" turret, putting it and its two guns out of action. Shrapnel swept the bridge, killing or wounding all bridge personnel except the captain and two others. Captain Bell's communications were wrecked. Communications from the aft conning position were also destroyed. The ship had to be steered via a chain of messengers for the rest of the battle.
Meanwhile, Ajax and Achilles closed to 13,000 yd (12,000 m) and started making in front of Graf Spee, causing her to split her main armament at 06:30 and otherwise use her 150 mm (5.9 in) guns against them. Shortly after, Exeter fired two torpedoes from her starboard tubes but both missed. At 06:37, Ajax launched her Fairey Seafox spotter floatplane from her catapult. At 06:38, Exeter turned so that she could fire her port torpedoes and received two more direct hits from 283 mm (11.1 in) shells. One hit "A" turret and put it out of action, the other entered the hull and started fires. Exeter was severely damaged, having only "Y" turret still in action under "local" control, with Jennings on the roof shouting instructions to those inside. She also had a 7° list, was being flooded and being steered with the use of her small boat's compass. However, Exeter dealt the decisive blow; one of her 8-inch shells had penetrated two decks before exploding in Graf Spee's funnel area, destroyed her raw fuel processing system and left her with just 16 hours fuel, insufficient to allow her to return home.
At this point, nearly one hour after the battle had started, Graf Spee was doomed since she could not make fuel system repairs of that complexity under fire. Two thirds of her anti-aircraft guns were knocked out, as well as one of her secondary turrets. There were no friendly naval bases within reach or reinforcements available. She was not seaworthy and could make only the neutral port of Montevideo.
Graf Spee hauled round from an easterly course, now behind Ajax and Achilles, towards the north-west and laid smoke. That course brought Langsdorff roughly parallel to Exeter. By 06:50, Exeter listed heavily to starboard and took water forward. Nevertheless, she still steamed at full speed and fired with her one remaining turret. Forty minutes later, water splashed in by a 283 mm (11.1 in) near miss short-circuited her electrical system for that turret. Captain Bell was forced to break off the action. That would have been the opportunity to finish off Exeter. Instead, the combined fire of Ajax and Achilles drew Langsdorff's attention as both ships closed the German ship.
Twenty minutes later, Ajax and Achilles turned to starboard to bring all their guns to bear, causing Graf Spee to turn away and lay a smoke screen. At 07:10, the two light cruisers turned to reduce the range from 8 mi (7.0 nmi; 13 km) even though that meant that only their forward guns could fire. At 07:16, Graf Spee turned to port and headed straight for the badly damaged Exeter, but fire from Ajax and Achilles forced her at 07:20 to turn and fire her 283 mm (11.1 in) guns at them, while they turned to starboard to bring all their guns to bear. Ajax turned to starboard at 07:24 and fired her torpedoes at a range of 4.5 miles (3.9 nmi; 7.2 km), causing Graf Spee to turn away under a smoke screen. At 07:25, Ajax was hit by a 283 mm (11.1 in) shell that put "X" turret out of action and jammed "Y" turret, causing some casualties. By 07:40, Ajax and Achilles were running low on resources, and the British decided to change tactics and move to the east under a smokescreen. Harwood decided to shadow Graf Spee and try to attack at night, when he could attack with torpedoes, better use his advantages of speed and manoeuvrability and minimise his deficiencies in armour. Ajax was again hit by a 283 mm (11.1 in) shell that destroyed her mast and caused more casualties. Graf Spee continued to the south-west.
Pursuit
The battle now turned into a pursuit. Captain Parry of Achilles wrote afterwards: "To this day I do not know why the Admiral Graf Spee did not dispose of us in the Ajax and the Achilles as soon as she had finished with the Exeter". The British and New Zealand cruisers split up, keeping about 15 mi (13 nmi; 24 km) from Admiral Graf Spee. Ajax kept to the German's port and Achilles to the starboard. At 09:15, Ajax recovered her aircraft. At 09:46, Harwood signalled to Cumberland for reinforcement and the Admiralty also ordered ships within 3,000 mi (2,600 nmi; 4,800 km) to proceed to the River Plate.