Several different cruising diagrams for the Battle Fleet itself, both by day and at night, were similarly drawn up. Some of these were specially designed to give such safety from submarine attack as was possible to the main body of the Fleet, in the not unlikely event of destroyers being absent, from bad weather, shortage of fuel, or other causes. The dispositions for use at night provided for the use of destroyer attack, and were designed to give safety from collision, due to squadrons inadvertently closing each other in the darkness, when showing no lights; this was a very possible event during the course of a long night when a very slight error in steering, or a slight difference in compasses, will rapidly bring two squadrons together that started the night five miles apart. It was necessary to keep squadrons separated, as a long line of ships greatly facilitated successful submarine attack, whilst a slight dispersal of squadrons gave greater freedom of movement in the case of destroyer attack. At the same time it was necessary to provide for concentrating the Fleet quickly at daylight.
The question of submarine screens was taken up at the commencement of war. This matter had naturally been considered before the War, but was in its earliest stages, and, although an efficient disposition of a screen of destroyers is a comparatively simple matter when there is no lack of destroyers, the case is different when a fleet is very short of the requisite number, as was our experience, and one destroyer had often to be disposed to endeavour to do the work of two.
Diagrams of submarine screens were, therefore, drawn up to meet the different conditions resulting from the presence of varying numbers of destroyers, or a decreased number of ships requiring to be screened, and also providing for the ships being in various formations. In November, 1916, the number of these diagrams was seventeen.
Early in the War the danger of successful submarine attack on warships at sea, whether in company or proceeding singly, had impressed on us the necessity of taking every precaution for safety, and the practice of the fleet steering zigzag courses was devised and generally adopted in accordance with my directions. In the case of a fleet or squadron, the usual practice was to carry out the alterations of course by turning the ships together; occasionally the turn was made “in succession,” but this was exceptional. In small squadrons, the turns were occasionally made at fixed time intervals without signal.
Zigzagging had a very beneficial effect on the manner in which officers of watches kept station in a fleet, since there is no better practice than keeping station on a line of bearing, a far more difficult matter to the novice than keeping station astern of another ship. I attribute the excellent manner in which the ships were handled in 1915 and 1916 very largely to this early experience. Much theoretical investigation was instituted to determine the method of zigzagging, both in a fleet and in a single ship, which gave the greatest protection against submarine attack, and actual experiments took place with our own submarines with a view to forming correct conclusions; the flag officers of the fleet rendered me much assistance in this as in all other matters.
The experience of the Grand Fleet was utilised in the instructions subsequently issued to merchant ships, and the value of zigzagging in reducing the danger of submarine attack was clearly shown during the year 1917 by the comparative immunity of merchant ships that complied with the orders as compared with those that did not do so. Occasionally, of course, zigzagging brought a ship into danger, but this was exceptional as compared with the general immunity given.
When the convoying of merchant ships through the submarine zone was instituted in 1917, after I had returned to the Admiralty, the Grand Fleet experience was again of value in the preparation of instructions.
The supremely important question of how best to handle in action the large and increasing Fleet engaged my attention from the commencement. In drawing up the various instructions for the conduct of the Fleet, both when cruising and in action, I availed myself of the advice and assistance of the experienced flag officers commanding the various Squadrons. Much discussion took place on these matters, and many of the dispositions adopted formed the subject of actual experiment at sea before being incorporated in the orders.
The successful and rapid deployment of the Battle Fleet from its cruising formation was a matter of the greatest importance, and constant practice in carrying out this manœuvre under every varying condition was given to the Fleet when at sea. Various arrangements were introduced having as their object the simplification and shortening of the manœuvre, with a view to bringing the heaviest possible fire to bear on the enemy’s fleet as quickly as possible. Orders were drawn up to meet cases of deployment in thick weather, when the enemy might be sighted at short range, and immediate independent action by a divisional Flag Officer would be necessary.
In the early part of the War the rapid deployment of the Fleet for action was complicated by the presence of the 3rd Battle Squadron of pre-Dreadnoughts—the vessels of the “King Edward VII.” class—as the speed of the ships of this squadron was some three knots less than that of the rest of the Battle Fleet. I endeavoured to solve this problem by practical experience. Much depended on the tactics likely to be adopted by the enemy’s Battle Fleet. The main difficulty lay in the fact that if the 3rd Battle Squadron was placed on one flank of the Battle Fleet when in cruising order and deployment towards that flank became necessary in conformity with an enemy movement, thus placing the slow 3rd Battle Squadron in the van, the fleet speed of the whole Battle Line was necessarily reduced to some 14 knots, in order to have the necessary reserve of speed in hand. If, on the other hand, the 3rd Battle Squadron was placed in the centre of the Fleet, the Fleet speed was again reduced to that attainable by this squadron. It was desirable to devise a cruising order for the Battle Fleet which would admit of the 3rd Battle Squadron being in the rear after deployment, in whichever direction deployment took place. There was still the objection, which had to be accepted, that a turn of 16 points forced upon us by the enemy would place this squadron in the van.