Action of 4 April 1941

The action of 4 April 1941 was a naval engagement fought during the Battle of the Atlantic during the Second World War. A German commerce raider, , ( to the , Raider E to the British) encountered the British armed merchant cruiser and sank it after a short engagement. The German crew rescued the British survivors, some of whom were repatriated and gave an account to the Admiralty. It was accepted that German commerce raiders were too well-armed for converted ocean liners equipped with obsolete guns but nothing else was available to the Royal Navy until later in the war.

Background

''Thor''

During the 1930s, the had paid banana plantations in Central America to have banana boats built by German yards, suitable for quick conversion for navy use. Such ships were faster than average freighters [] and sat lower in the water, making smaller targets. The (OPDR) banana boat ''Santa Cruz'' (3,862 Gross register tons [GRT]) was taken over by the and converted into the auxiliary cruiser (HSK-4 or to the , Raider E to the Admiralty) by Deutsche Werft AG. The ship was armed with six guns, one gun, two Flak, four Flak and four torpedo tubes. The raider also carried an Arado Ar 196A-1 floatplane for reconnaissance and had a complement of 349 officers and crew.

HMS ''Voltaire''

''Voltaire'', was built by Workman & Clark in 1923 as a passenger liner of the Lamport and Holt line, carrying passengers and freight between New York and Buenos Aires. The ship displaced , had a speed of and a crew of 269 men and officers. Used first as a troopship and then as an accommodation ship at Scapa Flow, it was later sent to Wallsend and equipped as an armed merchant cruiser (AMC). ''Voltaire'' carried eight and two naval guns, including at least one anti-aircraft mount. ''Voltaire'' patrolled the Mediterranean enforcing contraband regulations then sailed to Halifax, Nova Scotia to escort convoys across the Atlantic. Having refitted at Saint John, New Brunswick, ''Voltaire'' sailed for Trinidad and was then sent to Freetown in Sierra Leone to look for commerce raiders.

Prelude

On 6 June 1941, ''Thor'' ( Otto Kähler) sailed on a raiding voyage to the central and south Atlantic, disguised as the Russian merchant ship ''Orsk'', before sailing from Norway and passing through the Denmark Strait on 16 June. On 1 July, dressed up like a Jugoslav freighter, the Dutch ''Kertosono'' was intercepted and sent back to France as a prize. On 7 June the British ''Delambre'' was overhauled and sunk; two days later the Belgian ship ''Bruges'' was sunk. On 14 July, ''Gracefield'' hove to and was sunk; none of the ships got off a distress report. On 16 July, the British ship ''Wendover'' fought back and managed to transmit a report before being sunk by gunfire and torpedoes after the crew was taken prisoner, bringing the total to over 200 men. The Dutch ''Tela'', carrying food was captured the next day which alleviated the difficulty of feeding the captives.

On 28 July, ''Thor'' encountered the AMC at 24° 29' South, 33° 07' West, not far from Trinidade, about off the Brazilian coast. Wireless reports and overdue ships had indicated to the British that a raider was operating in the Atlantic and had sent ''Alcantara'' to investigate. ''Thor'' was armed with guns that considerably outranged the armament carried by ''Alcantara'' but ''Thor'' was slower and had to engage the AMC. In an engagement that lasted for about four hours, ''Thor'' inflicting serious damage and received two hits in return; ''Alcantara'' making slowly for Brazil. ''Thor'' sailed away to the south, behind a smoke screen, to complete repairs and rendezvous with a supply ship. On 26 September, in the south Atlantic, the Norwegian ship ''Kosmos III'' was sunk then the British ''Natia'' on 8 October; now carrying more than 360 prisoners. on 9 November ''Thor'' rendezvoused with the blockade-runner ''Rio Grande'' which delivered supplies and took off most of the prisoners.

On 5 December ''Thor'' met the AMC east of South America at 30° 52' South, 42° 53' West. ''Thor'' out-gunned and out-ranged ''Carnarvon Castle'' but was too slow to out-run the AMC. ''Thor'' inflicted so much damage with its stern armament that the AMC had to make for port for repairs. ''Thor'' rendezvoused with ''Admiral Scheer'' and a captured freighter on 25 December, from which supplies were generously replenished. Several British cruisers were concentrated off the River Plate and Rio de Janeiro but ''Thor'' met few ships, apart from German supply vessels for three months. ''Thor'' communicated information of its superiority against the British AMCs which gave the crews of other raiders greater confidence against them. On 25 March 1941, the passenger liner ''Britannia'' was sunk and the occupants left behind in lifeboats because ''Thor'' intercepted an RRR (raider report) call from ''Britannia'' and a reply from what the captain took to be a British warship nearby. Later that day ''Thor'' sank the Swedish ship ''Trolleholm''. In early April 1941, the AMC HMS ''Voltaire'' sailed from Trinidad in the Caribbean for Freetown, Sierra Leone and to search west of the Cape Verde islands for commerce raiders ''en route''.

Action

On 4 April ''Thor'' was back in the area to the north-east of Brazil, posing as a Greek freighter and at 06:15 its lookouts reported smoke on the horizon to port. The ship was HMS ''Voltaire'' (Captain James Blackburn); Kähler turned toward the vessel, not realising that it was an AMC and the British assumed that they had met a small freighter and closed on it to check. ''Voltaire'' sailed nearly straight at ''Thor'' from about ; at 06:45 and about , Kähler had the forward 150 mm gun fire a warning shot across the ship's bow. Kähler was surprised when the ship returned fire and replied with two guns; this time, an AMC was well within range and converging when the engagement began. The German gun crews managed to hit ''Voltaire'' with their opening salvo of four shells destroying the radio room before an RRR report could be sent and destroyed the fire-control system. ''Voltaire'' was set on fire in four minutes.

With its fire control system out of action, ''Voltaire'' could not synchronise its 6-inch guns and its fire became slow and inaccurate. At 07:15h, ''Voltaire'' was hit in the steering gear and began to turn in circles at a speed of . Blackburn abandoned the bridge when it was ablaze and went to the stern to command one of the two remaining 6-in guns but only managed to hit the top of ''Thors'' mast. Kähler fired two torpedoes from but neither hit ''Voltaire''. At about 08:00 Blackburn gave the order "abandon ship" and at 08:35 ''Voltaire'' rolled over and sank. ''Thor'' took aboard 189 survivors; 76 of the crew had been killed or died of wounds. In 55 minutes ''Thor'' had fired 724 rounds, inflicted many hits, for only minor damage.

Rather than leave the crew to be rescued, Kähler had the area was searched for five hours regardless of any ships appearing. ''Thor'' sailed north, changed disguise, rendezvoused with the tanker ''Ill'', then made course for Europe. German wireless broadcasts made much of the sinking of ''Voltaire'' but did not disclose the identity of the raider. When the Germans announced the sinking of ''Voltaire'', the Admiralty sent the Canadian AMC ''Prince David'' to search, which found wreckage half-way between Trinidad and the Cape Verde Islands. The British were ignorant of the details of the engagement until survivors were repatriated from Germany.

Aftermath

''Thor'' sank a Swedish freighter on 16 April, its eleventh success, a total of of shipping and one AMC. ''Thor'' reached the Bay of Biscay on 23 April and slipped up the Channel and arrived at Hamburg on 30 April. The Admiralty understood how inadvisable it was to fit obsolete guns on slow and old liners as trade protection vessels but lacked the modern guns and ships to take on German commerce-raiders until later in the war. ''Thor'' made another cruise in 1942 but was burned out in Yokohama, when the supply ship ''Uckermarck'' alongside, suffered an explosion and fire while its fuel tanks were being cleaned.

See also

* Single ship action
* Northern Patrol

Notes

Footnotes

References

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Naval battles of World War II involving Germany
Battle of the Atlantic
April 1941 events
Germany–United Kingdom military relations