This was a U-boat wolfpack operation off the east coast of Canada (27 May/26 June 1942).
The wolfpack comprised U-135, U-213, U-404, U-432, U-455, U-553, U-566, U-578 and U-653, and for the loss of none of its own number sank 11 ships (64,576 tons) and one seaplane tender.
The nine U-boats of the ‘Pfadfinder’ wolfpack operated in a number of locations off the east coast of North America against ships increasingly steaming in convoy rather than sailing independently. Korvettenkapitän Otto von Bülow’s U-404 was the most successful of the boats, sinking seven ships (31,051 tons) in the form of the 5,491-ton US Alcoa Shipper, 5,492-ton US West Notus, 1,345-ton Swedish Anna, 3,289-ton Yugoslav Ljubica Matkovic, 4,772-ton US Manuela, 3,845-ton Panamanian Nordal, and 6,827-ton Norwegian Moldanger. Fregattenkapitän Ernst-August Rehwinkel’s U-578 sank the 6,269-ton Dutch Polyphemus and 6,826-ton Norwegian Berganger. Kapitänleutnant Friedrich-Hermann Praetorius’s U-135 sank the 4,549-ton Norwegian Pleasantville, Kapitänleutnant Dietrich Borchert’s U-566 the 8,967-ton British Westmoreland, Kapitänleutnant Gerhard Feller’s U-653 the 840-ton US seaplane tender Gannet, and Kapitänleutnant Hans-Heinrich Giessler’s U-455 the 6,914-ton British tanker Geo H. Jones on the return journey.
The other three boats returned to base without claiming any sinkings.