'Tümmler' (ii) was a U-boat wolfpack operation, in concert with 'Unverzagt' and 'Wohlgemut', in the eastern Atlantic off North-West Africa and the western approaches to the Strait of Gibraltar (1/22 March 1943).
The wolfpack comprised U-43, U-66, U-202, U-504, U-521 and U-558, some of these boats refuelling from U-461, a 'milch cow' boat, between 27 February and 4 March, and for the loss of none of its own number sank two ships (12,354 tons), one in an attack on the ON.165 convoy and the other as an independent sailer.
On 3 March Oberleutnant Hans-Joachim Schwantke’s U-43 inadvertently sank the 5,154-ton German blockade runner Doggerbank (ex-British Speybank captured the raider Atlantis on 31 January 1941) during the later stages of her return from Japan to Germany but at a time considerably earlier than had been expected, with 7,000 tons of rubber, fish oil and other raw materials.
On 4 March Kapitänleutnant Carl Emmermann’s outbound U-172 sank the 8,049-ton British City of Pretoria and Kapitänleutnant Werner Henke’s U-515 sank the 8,300-ton British California Star in the area to the west of Spain. An operation by the 'Tümmler' (ii) wolfpack’s boats against a small southbound convoy, sighted by U-43 on 12/13 March, was denied any opportunity for success by the convoy’s strong air escort.