French destroyer Bourrasque and auxiliary patrol vessel Leoville
Joining with convoy 10-RS from Oran:
French minesweeper Chevreuil and armed trawlers L’Ajaccienne, La Setoise and La Toulonnaise

U-26 (Scheringer), U-37 (Hartmann) *, U-53 (Grosse) *

* U-boats that fired torpedo or used the deck gun

On 14 February, the convoy 65-KS had left Casablanca with 16 ships and was combined with the eight ships of convoy 10-RS coming from the Mediterranean off St. Vincent on 15 February. When the German radio intelligence reported that this convoy would be off Porto on 17 February, the BdU ordered U-26, U-37 and U-53 to search it. However, U-26 could not participate in the operation as she was low on fuel, so only U-37 could operate on the convoy when it was sighted by U-53 at 20.51 hours on 17 February.

Early on 18 February, the shadower sank the neutral Banderas astern of the convoy, apparently assuming that she was a straggler from the convoy. At 10.24 hours, U-53 attacked the convoy itself but her last torpedo detonated prematurely behind the Belgian steam merchant Garonne in station #31 and the U-boat was then chased away by La Setoise and La Toulonnaise. U-37 did not find the convoy, but sank a straggler.