On December 5 1940 one of Thor’s lookouts spotted a large and powerful ship emerging from a bank of sea mist a mere four miles away.
Kähler almost immediately recognised the 20,122-ton Armed Merchant-Cruiser HMS Carnarvon Castle, the fastest liner on the pre-war South Africa route, now armed with eight 6-inch guns, two 3-inch and with a top speed of 19 knots.
Hoping to avoid her, Kähler altered course, and for a time seemed to be succeeding, as the liner disappeared astern, but she was soon seen to be following the raider and rapidly closing with her.
Being in command of the only German raider with three 150mm guns aft, Kähler decided to force the enemy into a stern chase, but once he’d been asked to identify his ship, ordered to stop, and then fired upon, he had no choice but to run up his battle flag, drop his disguise and return fire.
By the fourth salvo the German gunners had found their target, but aware that once again the enemy was the faster ship, Kähler altered course to turn the chase into a circular fight in order to bring his full broadside into play.
While intermittently laying down smoke, Thor fired off two torpedoes, both of which missed, but as she was still undamaged, she was in total control of the action, circling and firing, and registering some significant hits, much to the obvious delight of her commander, who could clearly see the havoc his grimy and exhausted gunners were wreaking on the large enemy ship.
Their guns however, obsolete even before the first World War, were no longer up to such sustained action, with the recoil systems malfunctioning due to overheating and the barrels going out of train, but that no longer mattered, for suddenly, to everyone’s astonishment, the Carnarvon Castle ceased firing, made smoke, turned, and made off at top speed.
Flushed with pride in his ship and his crew, Kähler also ceased firing.
With 593 rounds fired, only a third of his 150mm ammunition remained.
But his ship was completely undamaged, he had suffered no casualties, and he was free to go anywhere he wished at his top speed of 18 knots.
This he did, knowing that the Royal Navy would mount a massive hunt for the German raider that had now hammered two of its Armed Merchant Cruisers.
His battered opponent, limping into Montevideo harbour on December 7 with four dead, thirty-two wounded, and a ten degree list, had taken twenty-seven hits.
Granted an extension to the 24-hour period permitted to warships in neutral harbours, her riddled hull had to be repaired before she was deemed seaworthy.
* With plates salved from the sunken wreck of the ‘Pocket Battleship’ Admiral Graf Spee.
After so many days of endless searching without any further success, Kähler was ordered to rendezvous with the Admiral Graf Spee’s sister-ship, the heavy cruiser Admiral Scheer, at point ‘Andalusia’ in order to transfer a number of men to serve as prize-crews on the Norwegian whaling-fleet captured by the raider Pinguin.