The first proposal for this device came from Portsmouth, where the Commander-in-Chief, Admiral the Hon. Sir Stanley Colville, was indefatigable in his efforts to combat the submarine; throwers manufactured by Messrs. Thornycroft, of Southampton, were tried and gave good results. The arrangement was one by which depth charges could be projected to a distance of 40 yards from a vessel, and the throwers were usually fitted one on each quarter so that the charges could be thrown out on the quarter whilst others were being dropped over the stern, and the chances of damaging or sinking the submarine attacked were thus greatly increased.
As soon as the earliest machines had been tried orders were placed for large numbers and the supplies obtained were as follows:
Deliveries commenced in July, 1917.
By September 1, 30 had been delivered.
By October 1, 97 had been delivered.
By December 1, 238 had been delivered.
COASTAL MOTOR BOATS
At the end of 1916 we possessed 13 fast coastal motor boats, carrying torpedoes, and having a speed of some 36 knots. They had been built to carry out certain operations in the Heligoland Bight, working from Harwich, but the preliminary air reconnaissance which it had been decided was necessary had not been effected by the end of 1916 owing to bad weather and the lack of suitable machines.
When winter set in it became impossible, with the type of aircraft then existing, to carry out the intended reconnaissance, and early in 1917 I abandoned the idea of the operations for the winter and sent the boats to the Dover Command for Sir R. Bacon to use from Dunkirk in operations against enemy vessels operating from Ostend and Zeebrugge. They quickly proved their value, and it became evident that they would also be useful for anti-submarine work. A large number were ordered, some for anti-submarine work and some for certain contemplated operations in enemy waters, including a night attack on the enemy's light cruisers known to lie occasionally in the Ems River, an operation that it was intended to carry out in the spring of 1918. A daylight operation in this neighbourhood, which was carried out during 1918, did not, from the published reports, meet with success, the coastal motor boats being attacked by aircraft, vessels against which they were defenceless. The new boats were of an improved and larger type than the original 40-feet boats. Delays occurred in construction owing principally to the difficulty in obtaining engines by reason of the great demand for engines for aircraft, and but few of the new boats were delivered during the year 1917.
MINING OPERATIONS
The policy which was carried out during 1917 in this respect, so far as the supply of mines admitted, aimed at preventing the exit of submarines from enemy ports. Incidentally, the fact that we laid large numbers of mines in the Heligoland Bight rendered necessary such extensive sweeping operations before any portion of the High Sea Fleet could put to sea as to be very useful in giving us some indication of any movement that might be intended. In view of the distance of the Grand Fleet from German bases and the short time available in which to intercept the High Sea Fleet if it came out for such a purpose as a raid on our coasts, or on convoys, the information thus gathered would have proved of great value.
In planning mining operations in the Heligoland Bight, it was necessary to take into consideration certain facts. The first was the knowledge that the Germans themselves had laid minefields in some portions of the Bight, and it was necessary for our minelayers to give such suspected areas a wide berth. Secondly, it was obvious that we could not lay minefields in areas very near those which we ourselves had already mined, since we should run the risk of blowing up our own ships with our own mines.
Mining operations had necessarily to be carried out at night, and as there were no navigational aids in the way of lights, etc., in the Heligoland Bight, the position in which our mines were laid was never known with absolute accuracy. Consequently an area in which we had directed mines to be laid, and to which a minelayer had been sent, could not safely be approached within a distance of some five miles on a subsequent occasion.