'Unverzagt' was a U-boat wolfpack operation, in tandem with 'Tümmler' (ii) and 'Wohlgemut', in the Atlantic off the western approaches to the Strait of Gibraltar against the UGS.6 convoy (12/22 March 1943).
The wolfpack comprised U-106, U-130, U-167, U-172, U-513 and U-515, and for the loss of Oberleutnant Siegfried Keller’s U-130 sank two ships (12,756 tons) and damaged one 7,200-ton ship in attacks on the UGS.6 convoy.
Before the 'Unverzagt' wolfpack and the 'Wohlgemut' wolfpack (formed with U-67, U-103, U-109, U-159 and U-524) could reach their planned patrol lines off the Azores islands group for the interception of a convoy whose imminence had been revealed by the B-Dienst naval signals intelligence branch, U-130 sighted and reported the UGS.6 convoy of 45 ships with Captain C. Wellborn’s US escort force (destroyers Wainwright, Champlin, Hobby, Mayrant, Rhind, Rowan and Trippe), but was then sunk by Champlin.
In the prevailing calm conditions, the U-boats found it difficult to approach the destroyers, which were equipped with radar which provided indications of the U-boats' presence but were not equipped with the HF/DF equipment which would have allowed the location of the boats' radio transmissions. Kapitänleutnant Carl Emmermann’s U-172 sank the straggling 5,565-ton US freighter Keystone during the evening of 13 March.
The force deployed against the UGS.6 convoy was then strengthened by the arrival of the 'Tümmler' (ii) wolfpack (U-43, U-66, U-202, U-504 and U-558). On 13 March U-167, U-172 and U-513, and on 14 March U-106, U-167 and U-513, were driven off and U-515 was depth-charged and damaged. On 15 March U-159 and Kapitänleutnant Walter Freiherr von Steinaecker’s U-524 tried to make submerged daylight attacks and the latter sank the 8,062-ton French freighter Wyoming. On 16 March U-106 brought up nine boats, but all the German attacks were beaten off or otherwise frustrated. Emmermann’s U-172 and U-524 made simultaneous submerged attacks into the evening, the former sinking the 7,191-ton US freighter Benjamin Harrison, but the U-boats missed Rhind and several tankers.
Early on 17 March U-558 missed the convoy, but during the evening of the same day U-167 torpedoed and damaged the 7,200-ton US freighter Molly Pitcher, which was later despatched by Kapitänleutnant Klaus Heinrich Bargsten’s U-521. On 18 March the Allied position was strengthened by the arrival of air support, and while U-524 was still able to maintain contact, attack was now no longer possible and the German effort was terminated on the following day.
On 22 March von Steinaecker’s U-524 was sunk, with the loss of all hands, by a Consolidated B-24 Liberator long-range anti-submarine aeroplane of the USAAF’s 1st Anti-Submarine Squadron.