During the night of 16th-17th March 1941 the U-Boats U-99 and U-100 were involved in a combined attack on convoy HX-112. A series of ships were torpedoed before U-100 was detected on ASDIC and subject to depth charge attack by HMS Walker and HMS Vanoc. Then in the early hours of the morning HMS Vanoc spotted U-100 on her recently installed Type 286M radar. This was the first confirmed British surface ship radar sighting of a U-boat. HMS Vanoc rammed U-100 – her commander Joachim Schepke was crushed against the periscope mast and was not one of the six survivors.
U-99 was commanded by Otto Kretschmer with a long list of sinkings to his name, among them the attack on convoy SC7 and the torpedoing of HMS Forfar. U-99 had used up all her torpedoes and was about to leave for her home port, creeping away on the surface. She spotted a destroyer, crash dived and then came within HMS Walker’s ASDIC. Naval Intelligence was able to compile the following sequence of events from interviews with the survivors:
As “U 99” was leaving the scene the Chief Quartermaster sighted a destroyer and gave the alarm. “U 99” crash dived. At about 0330 H.M.S. “Walker,” in approximate position 61° 16′ N., 12° 56′ W., was circling H.M.S. “Vanoc” to give her A/S protection while the latter picked up survivors from “U 100,” which she had rammed at about 0318.
At 0337 “Walker” obtained contact quite close to where “Vanoc” was stopped’ this was thought to be non-sub at first, but as the asdic operator insisted that contact was firm and the echo rapidly improved, the Captain decided to attack.
The crew of “U 99” heard the destroyer passing overhead, and then came the explosions of six depth charges, thought by the Germans to have exploded beneath the U-Boat which was then at depth of 120 metres (393.7 ft.).
“U 99” then went to about 140 metres (459 ft.), or deeper, and water entered the boat; according to the Captain she sank to about 185 metres (607 ft.) or more; but she suddenly started to rise quickly and surfaced; the conning tower hatch was thrown open and the Captain climbed out.
It was then about 0350. The German Captain’s intention was to try and get away on the surface but the Quartermaster reported that the steering gear was out of action; the electric motors were also out of action. The First Lieutenant connected the hand steering gear. But everything, including the fuel tanks, had been smashed. The crew had put on their lifebelts and hurried out of the U-Boat.
At 0352 “Walker” sighted “U 99” on the surface. “Vanoc” and “Walker” opened fire on “U 99” at 0354, but ceased firing two minutes later. At this juncture yet another U-Boat was reported astern by reliable witnesses in “Walker.” The Captain of “U 99” called out to his men that their U-Boat was sinking. The First Lieutenant and the Engineering Officer, estimating that their ship would remain afloat for another ten or fifteen minutes, started to open valves to make certain of sinking “U 99.”
As the First Lieutenant went forward, he suddenly heard splashing in the Control Room, and saw a stream of water coming in through the conning tower hatch. He therefore climbed out at once, and found the whole crew gathered together on the bridge.
As the U-Boat did not seem to be sinking fast enough, and it was feared that the British might try to board her, the Engineer Officer again went below to open wide the galley hatch which had previously been only partly opened. He never got out again, and the crew heard him shouting as the U-Boat sank.
The Captain said that a W/T message was sent in clear, just before “U 99” sank; but he did not know whether it was transmitted on full strength or not, or whether it had been received at his base. The signal read: “Depth charges – captured – Heil Hitler – Kretschmer.”
Kretschmer expressed the opinion that “Walker” had not located their U-boat by any detector gear, but had sighted “U 99” on the surface and had dropped depth charges which were effective more by luck than anything else. Five officers and 35 men were picked up by H.M.S. “Walker.” One officer and two ratings were drowned.
The whole report used to be available at the U-Boat Archive [ http://www.uboatarchive.net/U-99INT.htm]. It may be possible to access this from the internet archive.
The loss of U-47, U-99 and U-100, during March was a substantial blow against the U-Boat arm. Their three highly experienced and successful U-Boat commanders, Prien, Kretschmer and Schepke could not be replaced. But the Battle of the Atlantic had a long time still to run.
The Nazis eventually revealed the fate of U-99 and U-100 on the 25th April:
The submarines under the command of Lieutenant Commander Kretschmer and Lieutenant Schepke have not returned from patrol. Both boats were recently instrumental in destroying enemy convoys under the toughest conditions and have increased their overall successes considerably.
Lieutenant Commander Kretschmer now has in addition to the destruction of three enemy destroyers – including two on his last undertaking – sunk a total of 313,611 GRT, including the auxiliary cruiser “Laurentic”, “Patroclus” and “Forfar”. Lieutenant Schepke sunk 233,971 GRT of enemy shipping.
The two commanders, awarded with the Oak Leaves to the Knight’s Cross of the Iron Cross in recognition of their outstanding services in the freedom struggle of the German people, have won imperishable laurels with their brave crews. Part of the crew, among them Lieutenant Commander Kretschmer, was taken prisoner.