'Steinbrock' was a U-boat wolfpack operation in the Atlantic, in tandem with 'Pirat', against the ONS.115 convoy (29 July/3 August 1942).
The wolfpack comprised U-43, U-71, U-164, U-210, U-217, U-511, U-552, U-553, U-597, U-607 and U-704, and for the loss of Korvettenkapitän Rudolf Lemcke’s U-210 sank two ships (16,586 tons) and damaged two other ships.
On 29 July the outbound U-210 spotted and reported the ON.115 convoy of 41 ships supported by Lieutenant Commander D. C. Wallace’s Canadian Escort Group C3 (destroyers Saguenay and Skeena, and corvettes Agassiz, Galt, Louisburg, Sackville and Wetaskiwin).
On 30 and 31 July the escort successfully repelled several attempts by the U-boats which managed to make contact (U-164, U-210, U-217, U-511, U-553 and Kapitänleutnant Victor Vogel’s U-588), of which the last was depth-charged and sunk by Skeena and Wetaskiwin.
On 1 August the 'Pirat' wolfpack’s patrol line was established with U-164, U-210, U-217, U-511 and U-553, which were joined on the following day by the replenished U-43, U-71, U-454, U-552, U-597, U-607 and U-704 of the 'Wolf' wolfpack. During the night which followed, Saguenay and Skeena had to depart for refuelling, and only Louisburg, Sackville and Agassiz remained with the convoy after Wetaskiwin did not return from a hunt. In the afternoon two destroyers, the British Witch and Canadian Hamilton, arrived from the Western Local Escort Force.
On 2 August U-552 sighted the convoy and brought up U-71, U-217, U-553, U-597 and U-704. Kapitänleutnant Erick Topp’s U-552 torpedoed and damaged two ships, the 10,627-ton British G. S. Walden and 7,167-ton Belgian Belgian Soldier, the latter being sunk by Kapitänleutnant Ernst Mengersen’s U-607 at a slightly later time. Kapitänleutnant Karl Thurmann’s U-553 sank the 9,419-ton British Lochkatrine. Further attacks on the convoy’s ships by U-71, U-217 and U-552, and by U-597 on a straggler, all failed to gain success.
On 3 August the operation had to be broken off in conditions of thickening fog.