At 6 P.M. the _Falmouth_ reported the periscope of a submarine in sight inside the harbour, and immediately opened fire, four rounds being fired by this ship; she reported having probably hit the submarine. Directly afterwards the _Vanguard_, one of the outer line of battleships, also opened fire on an object reported as a periscope, as did one of the E class destroyers, which was patrolling between the Fleet and the Hoxa entrance. The 1st Light Cruiser Squadron was directed to weigh immediately steam was ready, which was at 8.30 P.M., and to endeavour to locate the submarine and keep her under. The 2nd Flotilla, lying at Longhope, at short notice, was also instructed to weigh at once and search for the submarine. The whole of the ships present were ordered to raise steam with all despatch, and to prepare for torpedo attack, and the small craft, such as drifters, steamboats, motor-boats, yachts, etc., which had steam ready and which could be collected, were at once organised in detachments to steam up and down the lines at high speed and outside the Fleet, with the object of confusing the submarine and endeavouring to ram her, if sighted. Colliers and store-ships which had steam ready were directed to weigh and to go alongside the battleships that were not fitted with torpedo nets, in order to act as a form of protection against torpedoes fired at these valuable vessels. All ships in the outer lines were directed to burn searchlights to locate and confuse the submarine. At about 6.30 P.M. the _Drake_ reported a submarine in sight from that ship, thus confirming the earlier reports. The Fleet was directed to weigh by divisions as soon as steam was ready and to proceed to sea. By 9 P.M. the weather was exceedingly thick inside the harbour and considerable difficulty was experienced in getting the Fleet out, as at this time there were no navigational facilities of any sort for leaving the harbour at night or in thick weather; but by 11 P.M. all the ships had left the harbour without accident, and, although there was a dense fog outside, the Fleet cleared the Pentland Firth successfully. The _Assistance_ was ordered to Loch Ewe, and left after the Fleet, reporting having sighted a submarine in the entrance whilst going out. The 2nd Flotilla was left behind to locate and, if possible, destroy the submarine, and the 4th Flotilla was stationed outside the Hoxa and Hoy entrances during the night, and directed to meet the Fleet at 7 A.M. on the 2nd. The only ship, as distinct from destroyers, remaining in the harbour was the _Cyclops_, lying off Scapa with the telegraph and telephone cables on board, and directions were given to Rear-Admiral Miller to endeavour to locate, by means of the mine-sweeping gunboats, the submarine reported sunk by the _Falmouth_.