'Wildfang' (i) was a U-boat wolfpack operation in the Atlantic, in tandem with 'Ostmark' and 'Westmark', against the SC.121 convoy (26 February/7 March 1943).
The wolfpack comprised U-84, U-89, U-359, U-409, U-432, U-448, U-591, U-638, U-664 and U-758, and for the loss of none of its own number sank one 6,116-ton ship.
For 25 February a new patrol line was established by the 'Wildfang' (i) wolfpack, which included boats returning from the attack on the ON.166 convoy and a number of others replenished by U-460. With the arrival in the Atlantic of the 'Burggraf' wolfpack on 26 February, the 'Wildfang' (i) wolfpack was relocated to the area north-east of Newfoundland for the task of intercepting convoys using the Allies' northern transatlantic route. The SC.121 convoy passed unobserved between the 'Wildfang' (i) and 'Burggraf' wolfpacks, but on 6 March U-405 of the latter’s boats sighted and reported this convoy of 59 ships, many of them stragglers after the convoy’s passage through severe gales. The convoy was supported by Commander Paul R. Heineman’s US Escort Group A3 (US Coast Guard cutter Spencer, destroyer Greer, Canadian corvettes Dauphin, Rosthern and Trillium, and British corvette Dianthus), together with the British rescue ship Melrose Abbey.
The 'Wildfang' (i) wolfpack’s sole success against the SC.121 convoy was the 6,116-ton British Empire Impala, which was sunk by Kapitänleutnant Hans-Jürgen Zetzsche’s U-591 on 7 March, the day on which the remaining boats of the 'Wildfang' (i) and 'Burggraf' wolfpacks re-formed as the new 'Raubgraf' wolfpack to the north-east of Newfoundland. On this day U-591 sank the 5,879-ton Yugoslav Vojvoda Putnik also of the SC.121 convoy.