'Burggraf' was a U-boat wolfpack operation in the Atlantic (26 February/6 March 1943).
The wolfpack eventually comprised 18 boats 1, worked with the 'Neuland', 'Ostmark', 'Westmark' and 'Wildfang' wolfpacks and, for the loss of none of its own number, sank one 2,868-ton ship of the SC.121 convoy from Sydney, Cape Breton island, to Liverpool.
On 26 February the 'Burggraf' wolfpack, then comprising U-228, U-527, U-230, U-523, U-526, U-616, U-435, U-615 and U-332, was created in the central part of the North Atlantic and the 'Wildfang' wolfpack, comprising U-638, U-89, U-432, U-758, U-664, U-84, U-409 and U-591, was moved into the area to the north-east of Newfoundland to intercept Allied convoys using the northern route. U-603, U-91, U-653, U-621, U-600 and U-468, newly arrived after replenishing from U-462, lengthened the patrol line of the 'Burggraf' wolfpack as it moved to the south-west until 4 March, and behind it U-634, U-709, U-566, U-405, U-359, U-659 and U-448 assumed waiting positions.
On 5 March the 57 ships of the ON.168 convoy, supported by Commander R. C. Boyle’s British Escort Group B5 (the destroyers Havelock and Volunteer, the frigate Swale and the corvettes Buttercup, Godetia, Lavender, Pimpernel and Saxifrage) passed through the 'Wildfang' wolfpack without being spotted as it steamed through a gap formed by the loss of Kapitänleutant Georg-Werner Fraatz’s U-529, which had been sunk on 15 February by a Consolidated Liberator four-engined maritime patrol bomber of the British No. 120 Squadron but had not yet been missed by the Germans. The SC.121 convoy also passed unobserved between the 'Wildfang' and 'Burggraf' wolfpacks, but on 6 March Korvettenkapitän Rolf-Heinrich Hopmann’s U-405 sighted the convoy scattered by nine consecutive days of a north-westerly storm and snow squalls. The storm had damaged the radio communication system aboard the escort commander’s ship Spencer, and Dauphin had to leave the convoy with damaged steering gear.
The convoy comprised 59 ships including many which, as a result of the severe weather, had become detached and were proceeding as stragglers. The convoy’s escort was Commander Paul A. Heineman’s US Escort Group A3 (the US Coast Guard cutter Spencer, the US destroyer Greer, the Canadian corvettes Dauphin and Rosthern, the British corvettes Dianthus and Trillium, and the rescue ship Melrose Abbey): three of the escorts had defective sonar, and three had unserviceable radar.
At this time Grossadmiral Karl Dönitz, by now commander-in-chief of the German navy but still exercising direct control of the U-boat arm, deployed 17 boats 2 as the 'Westmark' wolfpack and formed the 'Ostmark' wolfpack from the 'Neuland' wolfpack in a patrol line farther to the east for 8 March: this comprised U-229, U-665, U-641, U-447, U-190, U-439, U-530, U-618 and U-642. After U-405 had been driven off, U-566 and U-230 made contact with the convoy during the night of 6/7 March. Unnoticed by the escorts, Kapitänleutnant Paul Siegmann’s U-230 slipped in and torpedoed the 2,868-ton British Egyptian on the night of 6/7 March. The 6,116-ton British Empire Impala stopped to rescue survivors and was torpedoed after dawn by Kapitänleutnant Hans-Jürgen Zetzsche’s U-591, resulting in the loss of 7,628 tons of general cargo, oilseed, palm oil and tin ore.
On 7 March U-228, U-230, U-591, U-409, U-526 and U-634 maintained contact in spite of a storm punctuated by snow and hail showers, but were not able to attack. In the morning of 8 March the winds subsided but the visibility was still very variable: U-527 missed the convoy but another boat (probably Kapitänleutnant Hans Möglich’s U-526) sank the 3,921-ton British Guido that had become separated from the main body of the convoy. Kapitänleutnant Max Wintermeyer’s U-190 torpedoed the 7,015-ton British Empire Lakeland when the gale subsided on 8 March, and four more stragglers were sunk by U-526, Kapitänleutnant Herbert Uhlig’s U-527, Kapitänleutnant Hans-Jürgen Zetzsche’s U-591 and Kapitänleutnant Herbert Brünning’s U-642 (5,242-ton British Fort Lamy, 5,879-ton Yugoslav Vojvoda Putnik, 7,015-ton British Empire Lakeland and 2,125-ton British Leadgate respectively).
On 9 March the US Coast Guard cutters Bibb and Ingham and the US destroyer Babbitt reached the scene from Iceland as escort reinforcements. Liberator long-patrol patrol bombers of the RAF’s No. 120 Squadron operating from Northern Ireland also provided air escort and drove off U-566, which was the German contact-keeper boat. Of the U-boats coming up by nightfall, which included U-229, U-409, U-641, U-332, U-230, U-405 and U-665, two were bombed and four depth-charged by Babbitt, Rosthern and others. An attack by U-229 failed. In the evening of 9 March Kapitänleutnant Kurt Lange’s U-530 torpedoed the straggling 3,058-ton Swedish Milos, and during that night U-405 torpedoed the 4,665-ton Norwegian Bonneville while Oberleutnant Robert Scheletig’s U-229 torpedoed the 4,946-ton British Nailsea Court and Oberleutnant Hanns-Ferdinand Massmann’s U-409 torpedoed the 5,989-ton British escort oiler Rosewood and the 3,837-ton US ammunition ship Malantic. The cargo losses were 8,000 tons of ammunition, 14,856 tons of general cargo and explosives, steel and lumber.
On 10 March the wind strengthened once again to storm force and, in conditions of driving snow and hail, only U-229 and U-616, which fired unsuccessful torpedo salvoes, and briefly U-523 and U-642, came into contact with Allied merchant vessels sailing independently. In the afternoon U-634, the last contact-keeper, was driven off.
The convoy reached Liverpool on 14 March. Only 76 of the 275 crewmen of the sunk ships were rescued. The partial malfunctioning of the Allied naval vessels' radar and radio equipment, as a result of storm damage, greatly impeded the capabilities of the escorts, which were further reinforced during that day by the arrival of the British corvettes Campion and Mallow.
On 6 March six of the U-boats had left the pack to become the 'Westmark' wolfpack, and the other three boats disbanded on the following day.