It may not be out of place here to mention the organisation for getting the Grand Fleet to sea from its bases to any desired point of concentration with rapidity and safety, and of bringing the Fleet back into the bases in face of probable submarine or mine attack. As the Grand Fleet increased in size, and the danger from mine and submarine grew, so the problem of leaving Scapa Flow and re-entering that base with safety became more complicated. The necessity for the Fleet leaving harbour in the shortest possible time and with the fewest possible number of signals was obvious. Similarly on returning the various squadrons had to enter the base with the least practicable delay in order to avoid giving submarines engaged in watching the approaches an opportunity for getting into positions for attacking the squadrons in rear, after having sighted those in the van. The operations, both of departure and entry, were rendered all the more difficult owing to the very strong and erratic tides experienced in the Pentland Firth, while all ships navigating at night had to be navigated without showing lights. The usual method of departure from Scapa was as follows: A “Preparatory Signal for leaving Scapa” consisting of one word was made as soon as I decided to take the Fleet to sea. On receipt of this “Preparatory Signal” all ships raised steam for 18 knots at two hours’ notice. Patrol destroyers were recalled by the Commodore (F) for refuelling. All officers and men absent on patrol duty in drifters were also recalled, and every preparation was made for leaving harbour. The Admiral Commanding the Orkneys and Shetlands warned the outer patrols that the Fleet might be leaving shortly. Whilst the Fleet was raising steam in readiness to be off at two hours’ notice a signal was made which indicated the time at which the first squadron to leave was to move ahead from the anchorage, together with the speed to be maintained after passing the submarine obstructions. No further signals were necessary. The organisation provided for the order in which squadrons were to leave, as well as the interval between squadrons or divisions, which in daylight was usually one mile from the rear ship of one squadron, or division of four ships, to the leading ship of that following, or two miles at night. The organisation also provided for successive squadrons or divisions being taken alternately north or south of the Pentland Skerries if the Fleet proceeded to the eastward, in order that the interval between those following the same course might be increased.