The Crisis of the Naval War

by John Rushworth Jellicoe

A fact to which the Admiralty frequently directed attention was that, although annoyance and even serious inconvenience might be caused to the enemy by sea and air operations against Ostend and Zeebrugge, no permanent result could be achieved by the Navy alone unless backed up by an advance on land. The Admiralty was heart and soul for an audacious policy, providing the form of attack and the occasion offered a reasonable prospect of success. Owing to the preoccupations of the Army, we had to be satisfied with bombardments of the ports by unprotected monitors, which had necessarily to be carried out at very long ranges, exceeding 25,000 yards, and necessitating direction of the fire by aircraft.

Bruges, about eight miles from the sea, was the real base of enemy submarines and destroyers, Zeebrugge and Ostend being merely exits from Bruges, and the use of the latter could only be denied to the enemy by land attack or by effective blocking operations at Ostend and Zeebrugge, for, if only one port was closed, the other could be used.

Neither Zeebrugge, Ostend, nor Bruges could be rendered untenable to the enemy with the guns available during 1917, although Ostend in particular, and Zeebrugge to a lesser extent, could be, and were frequently, brought under fire when certain conditions prevailed, and some temporary damage caused. Indeed, the fire against Ostend was so effective that the harbour fell into disuse as a base towards the end of 1917. We were arranging also in 1917 for mounting naval guns on shore that would bring Bruges under fire, after the enemy had been driven from Ostend by the contemplated operation which is mentioned later. When forced to abandon this operation, in consequence of the military advance being held up by the weather, these guns were mounted in monitors.

In the matter of blocking the entrance to the ports of Zeebrugge and Ostend, the fact had to be recognized that effective permanent blocking operations against destroyers and submarines were not practicable, mainly because of the great rise and fall above low water at ordinary spring tides, which is 14 feet at Ostend and 13 feet at Zeebrugge for about half the days in each month. Low water at Ostend also lasts for one hour. Therefore, even if block-ships were sunk in the most favourable position the operation of making a passage by cutting away the upper works of the block-ships was not a difficult matter, and the Germans are a painstaking people. This passage could be used for some time on each side of high water by vessels like destroyers drawing less than 14 feet, or submarines drawing, say, 14 feet. The block would, therefore, be of a temporary and not a permanent nature, although it would undoubtedly be a source of considerable inconvenience. At the same time it was realized that, although permanent blocking was not practicable, a temporary block would be of use, and that the moral effect alone of such an operation would be of great value. These considerations, together with the abandonment of the proposed landing on the Belgian coast, owing to unfavourable military conditions, led to the decision late in 1917 to undertake blocking operations concurrently with an attack on the vessels alongside the Mole at Zeebrugge.

In order to carry out the general policy mentioned, the eastern end of the Straits of Dover had been heavily mined at intervals during the war, and these mines had proved to be a sufficient deterrent against any attempt on the part of surface vessels larger than destroyers to pass through. Owing to the rise of tide enemy destroyers could pass over the minefields at high water without risk of injury, and they frequently did so pass. Many attempts had been made to prevent the passage of enemy submarines by means of obstructions, but without much success; and at the end of 1916 a "mine net barrage"—i.e. a series of wire nets of wide mesh carrying mines—was in process of being placed by us right across the Straits from the South Goodwin Buoy to the West Dyck Bank, a length of 28 miles, it being arranged that the French would continue the barrage from this position to the French coast. The construction of the barrage was much delayed by the difficulty in procuring mooring buoys, and it was not completed until the late summer of 1917. Even then it was not an effective barrier owing to the tidal effects, as submarines were able to pass over it during strong tides, or to dive under the nets as an alternative; it was not practicable to use nets more than 60 feet deep, whilst the depth of water in places exceeded 120 feet.

Deep mines were laid to guard the water below the net, but although these were moored at some considerable distance from the barrage, trouble was experienced owing to the mines dragging their moorings in the strong tide-way and fouling the nets. One series had to be entirely swept up for this reason. Many devices were tried with the object of improving this barrage, and many clever brains were at work on it. And all the time our drifters with their crews of gallant fishermen, with Captain Bird at their head, worked day after day at the task of keeping the nets efficient.

In spite of its deficiencies the barrage was believed to be responsible for the destruction of a few submarines, and it did certainly render the passage of the Straits more difficult, and therefore its moral effect was appreciable. Towards the end of 1917, however, evidence came into our possession showing that more submarines were actually passing the Straits of Dover than had been believed to be the case, and it became a question whether a proportion of the drifters, etc., required for the maintenance of the nets of the barrage should be utilized instead for patrol work in the vicinity of the mine barrage then being laid between Folkestone and Cape Grisnez. This action was taken, drifters being gradually moved to the new area.

In April, 1916, a net barrage, with lines of deep mines on the Belgian side of the nets, had also been laid along the Belgian coast covering the exits from the ports of Ostend and Zeebrugge as well as the coast between those ports. These nets were laid at a distance of some 24,000 yards from the shore. This plan had proved most successful in preventing minelaying by submarines in the Straits of Dover, and the barrage was maintained from May to October, but the weather conditions had prevented its continuance from that date.

The operation was repeated in 1917, the barrage being kept in position until December, when the question of withdrawing the craft required for its maintenance for patrol work in connection with the minefield laid on the Folkestone-Grisnez line came under discussion.

The Belgian coast barrage being in the nature of a surprise was probably more useful as a deterrent to submarine activity in 1916 than in 1917. In both years a strong patrol of monitors, destroyers, minesweepers, drifters for net repairs, and other vessels was maintained in position to the westward of the barrage to prevent interference with the nets by enemy vessels and to keep them effective.