U-176, a Type IXC under Rainer Dierksen entered the area on the 29th of April 1943 on the by-now familiar trajectory from south of Bermuda, this patrol aimed for the Mona Passage instead of the Windward Passage. Aged 35, Dierksen and the boat were on their third and final patrol together – a cruel fate awaited them at the hands of the Cubans on the border with Bahamian territorial waters a fortnight into the future.
For one week U-176 headed almost due south, ending off the mouth of the Mona Pass on the 8th of May. On that day instead of entering the Mona Passage, Dierksen opted to head due west along the coast of Hispaniola, also bypassing the Windward Passage on the 11th in favor of a cruise up the Old Bahama Channel.
When the submarine sank the Mambi and the ammonia tanker Nickeliner (one of the only such ships of its kind) on the 13th of May south of Andros Island, the activity did not go unnoticed. In fact both US and Cuban Naval forces picked up on the Mayday messages, and began tracking the course of the sub up the channel. By the time U-176 reached the Saint Nicholas Channel a convoy with Cuban escorts was awaiting to attack and destroy the boat on the 15th of May.
In an attack which was so efficient its success was not believed by the Americans for decades (in fact until a film crew confirmed the location of the submarine in 2002), a small Cuban patrol boat depth-charged the submarine into submission and, having sunk its prey, proceeded in an almost cavalier way to have lunch in a nearby port. This U-boat, aside from U-84 which was hundreds of miles from land, is the closest of any sunken enemy submarine to the Bahamas inasmuch as it lies some twenty miles or less from the Bahamian side of the Saint Nicholas Channel and the Bahamian territory of Cay Sal Bank. More on this incident later.
Dierksen was a Korvettenkapitän with eleven sinkings of 45,870 tons and one ship damaged for 7,457 tons in 216 sea days during three patrols. Known for his dogged pursuit (he once spent 48 hours and eight torpedoes sinking the Dutch freighter Polydorus), Dierksen was no greenhorn, sailing with the Tenth Flotilla out of Lorient. The submarine’s loss can be attributed as much to the efficient skill of the Cuban attackers as well as a bit of luck and the aggression of Dierksen in going after an escorted convoy in daylight.
The formerly American Cuban patrol boat CS 13 sank U-176 in deep water with a three-charge pattern of depth-charges with the result that four of them exploded on the submarine. Also a US Navy patrol plane – an American Vought-Sikorsky OS2U 3 Kingfisher aircraft out of the VS-62/1 Squadron assisted in vectoring the attackers to the U-boat.
Rainer Dierksen had been promoted to Korvettenkapitänonly two weeks before his death, and during the same patrol. The recipient of the U-boat War Badge of 1939 in February of 1943, he was awarded the German Cross in Gold in January of 1944 – posthumously. He joined the Reichsmarine in 1933 and started off in minesweeping flotillas, taking command of the 32nd Flotilla until March of 1941, when he joined the U-boat arm. In December 1941 he commissioned the Type IXC U-176 in Bremen.
SOURCES: Gudmundur Helgason, Rainer Kolbicz, www.uboat.net, 2011, Kenneth Wynn, U-boat Operations of the Second World War, Volume 1 and Volume 2, 1997