This was a U-boat wolfpack operation in the Atlantic against the ON.131 convoy (26/30 September 1942).
The wolfpack comprised U-221, U-258, U-260, U-356, U-407, U-410, U-437, U-575, U-582, U-595, U-597, U-599, U-607, U-615, U-617, U-618 and U-755, and neither lost any of its own number nor sank any ship.
On 26 September U-617, while heading toward the SC.100 convoy, spotted and reported the ON.131 convoy, which was supported by Lieutenant Commander D. C. Wallace’s Canadian Escort Group C3 (destroyers Saguenay and Skeena, and corvettes Agassiz, Gait, Sackville, Wetaskiwin and British Anemone). The U-boat then attacked, but was defeated by torpedo defects and the convoy’s skilful use of HF/DF data to pinpoint the attacker’s location before taking evasive action.
From the boats which had become widely scattered after the operations against the RB.1 and SC.100 convoys, U-176, U-216, U-221, U-258, U-356, U-373, U-410, U-569, U-595, U-599, U-607, U-615, U-617, U-618 and U-755 were ordered to concentrate as the ‘Tiger’ (v) wolfpack. Contact with the convoy was lost, however, and a systematic search then proved impractical as a result of the boats’ scattered positions and an imminent storm. The Germans therefore called off the undertaking, and eight of the boats then proceeded to the south to refuel in equal numbers from U-116 and U-118.