During the absence of the Fleet, the German submarine U 18 was rammed at 12.20 P.M. November 24th by mine-sweeping trawler No. 96, one mile off the Hoxa entrance to Scapa. U 18 was damaged in the collision, dived, hit the bottom and received further damage. All the available patrol craft were ordered to the spot most promptly by the Vice-Admiral commanding the Orkneys and Shetlands and hunted her. She finally came to the surface and surrendered off Muckle Skerry in the Pentland Firth. The submarine sank as the crew came on deck, the sea cocks, probably, having been previously opened. The commanding officer of the submarine, who had apparently intended to try to enter Scapa Flow, expressed great surprise to Admiral Colville at the absence of the Fleet. It seemed possible that he had been deterred from his attempt by the sight of the buoys across the entrance, probably suspecting the presence of an obstruction which, however, was not there. The sinking of the submarine caused the greatest gratification to the local defence forces at Scapa and acted as an incentive to further efforts. It was also, probably, a deterrent to further attacks on the Fleet at Scapa, as the circumstances in which U 18 was sunk were kept most secret in order that the enemy might be led to think that her destruction was due to nets or mines. Indeed, it is very likely that this incident and the secrecy observed had important results in preventing the loss of ships of the Grand Fleet when at anchor in Scapa Flow.
Great submarine activity occurred at this time in the vicinity of the Orkneys and Shetlands. The Dryad sighted a submarine on the 24th in Lat. 58.35 N., Long. 1.45 W.; a second was sighted by an armed trawler off Copinsay on the same day; and a third was sighted from the shore, proceeding to the eastward through the Pentland Firth. On the 25th U 16 was sighted by a collier and trawler in Lat. 58.46 N., Long. 2.15 W., and later by the mine-sweeping gunboat Skipjack not far from this position.
On the return of the Fleet arrangements were made for constructing, with Fleet resources, net obstructions across the Hoy entrance to Scapa Flow, and, in view of the attempt of U 18, all patrols were stiffened to the utmost extent possible.
During November 27th and 28th the strong gale continued, interfering considerably with the work on the submarine obstructions. Several reports of the sighting of submarines in harbours in the north of Scotland, the Orkneys and Shetlands were received during the last days of November, and destroyers and patrol craft were kept very busy in searching the various bays and harbours. In many cases charges were exploded on the bottom in bays in which it was considered that a submarine might be lying, in the hope of forcing her to the surface. No known result, however, was obtained.
The Fleet remained in the various bases until the end of the month, the ships in Scapa Flow carrying out gunnery and torpedo practices and working at the obstructions. The King George V., which had just returned from refit at a dockyard, developed condenser defects necessitating partial retubing; she was the fourth battleship in which this defect had occurred since the War started, a period of only four months, and it will be realised that such wholesale breakdowns caused me uneasiness.
During November the work of sinking block-ships in all the entrance channels to Scapa Flow, except the Hoxa and Hoy entrances, was carried out. Unfortunately the block-ships had been sent up in a light condition without cement ballast which, I was informed, could not be supplied, and they began in many cases to break up or to shift their position during the winter gales. This fact, combined with the great difficulty experienced in sinking them in the exact positions required owing to the strong tides prevailing (up to at least eight knots in strength), and the very short periods of slack water, rendered the work of blocking only partially effective.
At the end of November the effective state of the Grand Fleet was as follows:
Fleet-Flagship: the Iron Duke.
1st Battle Squadron:
7 ships, the Neptune being away refitting.
2nd Battle Squadron:
7 ships, of which one, the King George V., was disabled, retubing condensers.