The matter was at once represented to the Admiralty and proposals were made for blocking all the entrances to Scapa Flow, except the Hoxa and Hoy entrances, by sinking old merchant ships in the channels. Pending the supply of reliable defences for the main entrance, Rear-Admiral Miller was directed to requisition a large number of net-drifters. The plan was to lay drift nets in the entrance to be watched by the drifters, the nets having indicator buoys attached to them and floating on the surface, so that the presence of a submarine might be indicated by the buoy moving with the net.
The navigational difficulties of the narrower entrances were, meanwhile, the only obstacles to the passage of submarines through them, but it was realised that these were considerable. The opinion was formed, however, that the Hoxa entrance presented no insurmountable difficulty of this nature to a determined submarine commander.
By this date the local defence flotilla of destroyers consisted of vessels of the E class. A request was made for basing a hunting flotilla of 16 trawlers on Kirkwall, these vessels being intended to guard the approaches to the Pentland Firth and to act as submarine hunters generally. It was also suggested that a monetary reward should be offered to the personnel of any trawler through whose agency a submarine was captured or destroyed.
The mine-sweeping force at Scapa had been strengthened by the addition of a flotilla of trawlers, and the mine-sweeping gunboats and trawlers were continuously employed in keeping certain fixed channels of approach to the Pentland Firth swept and clear of mines. These vessels were, therefore, not available for anti-submarine work, except to the detriment of their mine-sweeping duties.
On September 1st the available cruiser squadrons were employed in Area No. 6, supported by the 3d Battle Squadron and the 1st Battle Cruiser Squadron.
From September 1st to September 5th the Battle Fleet remained at sea, cruising in the area between the north-east coast of Scotland and the coast of Norway, in support of the cruiser squadrons working to the southward, and opportunity was taken to continue the exercises of the Fleet in battle tactics, together with occasional gunnery practice. The Orion, of the 2nd Battle Squadron, was still absent from the Fleet, retubing condensers; the King Edward VII. rejoined on the 2nd, after exchanging defective guns; and the Dominion was then detached to Devonport to exchange her damaged 12-inch guns.
The 1st Battle Cruiser Squadron had been strengthened by the arrival of the Inflexible from the Mediterranean, and was employed during this period in support of the cruiser sweeps, the Squadron joining the Battle Fleet on the 3rd for battle exercises.
During the period under review reports from time to time of the sighting of enemy submarines appeared to indicate that they were working on a line Ekersund-Pentland Firth, the line which they were apparently occupying during the first few days of the War, when U 15 was sunk by the Birmingham.
Information received on September 3d suggested that enemy cruisers might have passed, or might be intending to pass, into the North Sea via the Skagerrak. The 2nd and 3rd Cruiser Squadrons and the 1st Light Cruiser Squadron, supported by the 1st Battle Cruiser Squadron and accompanied by the 2nd Flotilla, were, therefore, directed to sweep to the entrance to the Skagerrak, arriving there by noon of September 4th, starting from a position in Lat. 58 N., Long. 2.36 E., at 4 A.M. that day. From the Skagerrak the 2nd and 3rd Cruiser Squadrons were to make a detour to the south-westward with the 1st Battle Cruiser Squadron, the latter proceeding then to Rosyth and the Cruiser Squadrons to Cromarty; and the 1st Light Cruiser Squadron, with the 2nd Flotilla, was directed to sweep on a wide front towards the Pentland Firth on the Ekersund-Pentland line in search of enemy submarines, which it was hoped might be caught on the surface at night. Thence the 1st Light Cruiser Squadron was to proceed to Scapa to fuel, and the 2nd Flotilla to the westward of the Orkneys to search for submarines, returning to Longhope at 9 P.M. on September 6th. The 4th Flotilla, which had been with the Battle Fleet, was directed at the same time to sweep the western portion of the Ekersund-Pentland line for submarines, and then to return to Longhope.
These orders were carried out, but no enemy vessels of any sort were sighted, except that at 6.30 A.M. on the 5th the Thetis, mine-layer, working south-eastward of the Orkneys, reported a suspicious vessel, thought to be a German cruiser. The 2nd and 6th Cruiser Squadrons and 1st Light Cruiser Squadron closed in on the position, but the ship was eventually identified as one of our own vessels.