ADM 53/63190, ADM 137/3898, T1022, Roll 74, PG61969


Final Patrol:
(6) For his next patrol, von Lilienstern was instructed to mine the Kirkwall and Lerwick roads. Both were known to be heavily guarded and all concerned recognised the perilous nature of the mission. UC 55 left Helgoland on 25 September 1917.

and von Lilienstern had instructions to lay mines at the entrance to Shetland harbours of Kirkwall and Lerwick. The mines were to be laid in equal numbers and at irregular distances, but no more than five miles from the shore. By the afternoon of 29 September the boat entered the Southern Lerwick roads, the proposed site of her minelay. The boat was at periscope depth. To his dismay directly ahead von Lilienstern could discern the forms of a destroyer and at least one Auxiliary patrol vessel. The Commander decided to wait for these vessels to disperse. Finally, with the British warships nowhere to be seen, von Lilienstern issued orders for the minelay to begin.

Lt. Sauer:
'UC 55 was just preparing to lay mines when at a depth of twenty metres she lost trim and began to crash-dive. The captain tried to haul her on an even keel by rushing the crew aft. Eventually, when the boat had reached fifty metres the descent was stopped by blowing water out of her tanks. This caused her to rise twenty metres. Her motors were slowed and tanks vented to prevent her from breaking surface. Unable to sustain the pressure of the uncontrolled dive, the hull plating gave way and water rushed in, producing chlorine gas. At the same time the battery caught fire'

Everything that was not fastened down securely, tumbled forward and the crew who were not hanging onto something, were also flung down the boat. The engineering officer blew the forward tanks but the stern dropped and now he was forced to blow the aft tanks to compensate. The result was that UC 55 boat was seesawing alarmingly.

Obermachinistenmaat Kegelmann offered this post war account:
'The boat went down with a sharp bow-down angle. The Chief Engineer could not keep her on an even keel and we again went through the repetitions of being down by the bow one moment and then quickly down by the bow the next. The commands were continuous, ‘blow forward, blow aft pump the forward bilge-pump the aft-bilge'

As UC 55 broached helplessly, she was spotted by lookoutd on the armed trawlers, Sylvia, Tirade and Movavia.

Lt. Sauer:
"A fire broke out in the electric motor room and a cable to the main switchboard burnt through, then chlorine gas began developing. We were unable to find the source of the flooding. There were only sixty-five kg of compressed air left and the captain ordered all the tanks blown as soon as the boat surfaced, the watch officer, chief engineer and navigator went out onto the conning tower with the captain. The order came down to start the diesel engines and I went back to the control room. Just as I arrived, the helmsman shouted, ‘The rudder is not answering the helm’. The batteries had failed and there was no power for the rudder motor. The rudder was over ten degrees and the boat was running in a circle. While we were coupling the rudder to the manual controls the order came down to destroy the secret papers, codebooks and log. Another order directed us to set explosive charges in the mine-room and in the engine-room. While we were placing the charges, a round exploded against the conning tower, killing six men including Lt. Ing. Kirst. We finished setting the charges and activated the time fuses, and went out on deck. Maschinistenmaat Hansen and I went through the conning tower hatch and as we came out the captain said to Hansen, 'Hansen, the boat is not sinking quickly enough. Please go below and open the flooding valves on all the tanks.’ Hansen went below, did that and returned to the captain. By the time he got there the boat was already down by the stern."

Obermachinistenmaat Kegelmann:

“A trawler altered course towards us and several destroyers appeared. Vents were opened (tank No.1) explosive charges were not fired. Von Lillenstern went down with the boat. The trawler Tirade fired a shot, which hit the conning tower and a second shot struck the bow detonating a torpedo. Yet another struck the stern as the boat was sinking. We went over the side and swam away. We had not gone far when a violent explosion tore UC 55 apart and she vanished. A little while later there were two more explosions. There were destroyers and fishing boats all around us and after about a half an hour they picked us up.”

At the time of the UC 55 episode, HMS Tirade had just left Lerwick, under orders to join an inbound convoy. Her log makes interesting reading:
‘14.15 Sighted S/M on surface about three miles distance. Challenged. Ran full speed towards him.
14.28 Opened fire. Third and Fifth rounds hit.
14.32 Geman subarine sunk. Crew abandoned. Dropped depth charges which apparently exploded mines in submarine
Set course for Lerwick’

The Log gives the position of this attack as 60° 2N 0° 57.0W, off Helli Ness. Seventeen officers and men mere picked up but the following, including von Lilienstern, perished