An hour and a half afterwards Lieut.-Commander Birnie returned, after verifying his position, and found very large quantities of oil rising about fifty yards from his buoy. He dropped a third depth-charge and another buoy, and patrolled the neighbourhood all night. Sweepers arrived next day, located the U-boat with a bottom sweep in thirty fathoms, lowered a depth-charge on the sweep wire and blew the wreck up. For this ‘speedy and faultless attack’ Lieut.-Commander Birnie received the D.S.O., Lieutenant Isdale the D.S.C., and two A.B.’s the D.S.M. This feat was a remarkable one, for it was performed in almost total darkness; but success was achieved in even more difficult circumstances by P. 51 towards the end of March 1918. It was 8.30 in the evening; the sea was calm under the moonlight, but great spaces of it were darkened by cloud shadows. The commander, Lieutenant William Murray, R.N.R., was in the chart-house, and Mr. Whittel, the gunner, on watch, when the signalman on the bridge reported a submarine on the surface, about one point before the port beam and less than 300 yards away. Orders were at once given to increase to full speed, and starboard the helm to ram. As the ship swung, the commander reached the bridge and took charge. He could see the enemy’s wash and bow wave. Then she appeared more distinctly as a large U-boat, 350 feet long, with a huge conning-tower and about two feet of freeboard showing. P. 51 continued to swing into the desired position and the moment for a successful ram seemed to have arrived. Then occurred one of those sudden and unforeseen accidents which try a commander’s presence of mind and decision to the utmost. To strike the U-boat fair it was, of course, necessary to put the helm over as soon as P. 51’s head had swung far enough to be pointing for her, and so steady the ship on her course. But this order could not be obeyed--the helm had jammed. Lieutenant Murray knew that to struggle with it could only at best result in a bungling collision which would injure his own ship rather than the enemy. He made a lightning act of renunciation, kept his helm a-starboard and swung completely round, passing close along the submarine’s side and then turning altogether away from her. The helm was soon afterwards found to be acting again; but in the meantime P. 51 had lost sight of the enemy.