[4] Graf Spee had sailed into the South Atlantic in August 1939, before the war began, and had begun commerce raiding after receiving the appropriate authorisation on 26 September 1939.

[5] 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.

Ajax and Achilles shadowed the German ship until she entered the port of Montevideo, the capital of neutral Uruguay, to effect urgent repairs.

During the period before and at the immediate 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.

Olynthus was also directed to keep observation between Medanos and Cape San Antonio, off Argentina south of the River Plate estuary (see chart below).

[4] 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.

A Norwegian freighter saw Admiral Graf Spee practising the use of her searchlights and radioed that her course was toward South America,[16] the three available cruisers of Force G rendezvoused off the estuary on 12 December and conducted manoeuvres.

[7] 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.

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.

[7][16] 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.

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.

[17] 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.

It outlined British activity in the River Plate area and included information that Ajax, Achilles, Cumberland and Exeter were patrolling the South American coast.

[7] 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.

Lieutenant-Commander Richard Jennings, Exeter's gunnery officer remembers:[20][21] 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!

[20] 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.

Since the estuary had sandbanks, Harwood ordered Achilles to shadow Admiral Graf Spee while Ajax would cover any attempt to double back through a different channel.

The port of Mar del Plata on the Argentine coast and 200 mi (170 nmi; 320 km) south of Montevideo would have been a better choice for Admiral Graf Spee.

Also relevant was Article 16 of which part reads, "A belligerent war-ship may not leave a neutral port or roadstead until twenty-four hours after the departure of a merchant ship flying the flag of its adversary".

Initially, the British diplomats in Uruguay, principally Eugen Millington-Drake, made several requests for Admiral Graf Spee to leave port immediately.

[1] After consultation with London, which was aware that there were no significant British naval forces in the area, Millington-Drake continued to demand for Admiral Graf Spee to leave.

[31] At the same time, he arranged for British and French merchant ships to steam from Montevideo at intervals of 24 hours, whether they had originally intended to do so or not, thus invoking Article 16.

In fact, the two cruisers had been joined only by Cumberland, which had arrived at 22:00 on 14 December, after steaming 1,014 nautical miles (1,878 km; 1,167 mi) from the Falkland Islands in 34 hours, at an average of over 90% of her full trials speed attained over much shorter distances.

Overwhelming British forces (HMS Renown, Ark Royal, Shropshire, Dorsetshire, and Neptune) were en route but would not assemble until 19 December although they could intercept earlier if Admiral Graf Spee headed north or north-east from Montevideo shadowed by Cumberland and her smaller consorts.

For the time being, the total force comprised the undamaged Cumberland with a full ammunition load, and the damaged Ajax and Achilles with depleted stocks of shells.

Even the only actual British newcomer, the previously-unengaged Cumberland, could fight at full capacity for about 90 minutes and pursue at equal or higher speed for at least another 2,000 nautical miles (3,700 km; 2,300 mi) before she required replenishment at sea.

Ultimately, he chose to scuttle his ship in the River Plate estuary on 17 December to avoid unnecessary loss of life for no particular military advantage, a decision that infuriated Adolf Hitler.

Lieutenant Atwill, who wrote an account of the battle in which he served on Exeter, detailed the damage done and the emergency repairs to make the ship seaworthy enough to reach Stanley, Falkland Islands.

[49] Rows of simple crosses in the Cementerio del Norte, in the north of the city of Montevideo, mark the burial places of the German dead.

According to an article in the German language paper Albertaner on 6 October 2007, Steve Parish, the mayor of Ajax, defended the decision, declaring that Langsdorff had not been a typical Nazi officer.