Horst Uphoff in U-84 began his second and final patrol to the region on the 6th of July 1943, entering in a line to the west from midway Bermuda-Anegada. To leave Biscay U-84 sailed in company with U-306 and U-732. The boat was refueled by U-536 late in June west of the Azores (Wynn, Vol. 1, p.64). Like Carlsen’s before it, this fifteen-day incursion was to bear no fruit for the Axis – only for the Allied defenders.
It appears from the chart of the boat’s war log (KTB) that the submarine entered the Windward Passage on the 12th of July, by-passing the Turks and Caicos in favor of the route along the south of those islands, however the data is ambiguous. Whether Uphoff utilized the Caicos Passage or not, it left the area on or about the 12thof July. On the 16th of July Uphoff reported torpedoing a ship in the Yucatan Channel and leaving it burning, however this is unsubstantiated.
Continuing on a patrol unmarked by attacks, U-84 passed Guantanamo, by now a formidable Allied fortress, albeit one crammed with targets awaiting convoy deployments. Uphoff headed west to a point in the middle of the Gulf of Mexico after transiting the Yucatan Channel and on the 30th of July he re-entered the Bahamas region to the south of Key West and west of Cay Sal, Bahamas.
Opting for the Straits of Florida over the Old Bahama Channel, the boat proceeded in the Gulf Stream to Great Isaacs’s Light north of Bimini, rounding it to starboard on the 2nd of AuguSaint During that evening U-84 steamed passed the Berry Islands and Nassau, emerging from the Northeast Providence Channel on the 3rd. The 4th, 5th 6th, and 7th of August would be the last days of life for U-84’s entire crew.
Two reasons for the uncertainty of U-84’s route home are starkly simple: in order to avoid attracting the kind of attention to itself that saw the demise of Rostin in U-158 off Bermuda earlier in the war and others after him, Uphoff would have transmitted his daily position to home base (BdU) as rarely as possible in order to avoid radio-direction-finding (RDF) detection by the enemy.
Secondly, the submarine was sunk during the patrol northeast of Bahamas on its return leg, and thus there will never be an opportunity for historians and naval officers to study the actual log books of the patrol. As we shall see, even the dilemma of where and by whom the sub was sunk remained murky and erroneous until expert Dr. Axle Niestlé solved the riddle less than a decade ago.
We know that the boat was supposed to rendezvous for fuel from U-760 some 750 miles southwest of the Azores, and Wynn gives credit to the USS Core’s aircraft for a fatal attack on U-84 on the 24th. Specifically a US Avenger flown by Lt. W. A. Felter is given credit (Wynn, Vol. 1, p.64).
In fact, on the 7th of August, while still a day’s steaming from the eastern border of the Bahamas region, the boat was detected and attacked by an American B 4 Liberator aircraft, from the VB-105 squadron, of the US Navy. An Mk 24 homing torpedo sent U-84 to the bottom of the Atlantic with all hands in a position of 27.55 degrees north and 68.03 degrees west, roughly midway between Bermuda and the Turks & Caicos Islands.
Since U-84 and Kapitänleutnant Uphoff had already patrolled the region, his exploits have been catalogued above. Aged 26 at the time of his death, he was awarded the German Cross in Gold in January 1944 once it was clear that he and his crew were on what is euphemistically called in the submarine service an “eternal patrol”.
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, Clay Blair, Hitler’s U-boat War, The Hunters, 1939-1942, and Hitler’s U-boat War, The Hunted, 1942-1945, 2000