The operations are worth examining on three quite independent grounds. First, what is the strategical value of their objective? How, that is to say, would the naval activities of Great Britain and her Allies gain by Zeebrügge and Ostend being, for some months at least out of action? And, conversely, what would the enemy lose? Unless we are satisfied that the gain must be substantial—apart altogether from the moral effect—we should obviously have a difficulty in justifying, not the losses in ships incurred, which were trivial and easily replaced, but the losses in picked men, which were irreparable. Secondly, the incident is clearly worth examining for its tactical interest. What were the difficulties the vice-admiral in command had to overcome? By what weapons, devices, and manœuvres did he attempt to effect his purpose? Third, what was the moral effect?
STRATEGICAL OBJECT
There is now only one theatre of the war, and in this the issue of civilization or barbarism must be decided by military action. The event depends upon the capacity of the sea power of the Allies to deliver in France all the fighting men and all the war material that Allied ships can draw from Asia, from Australia, from South America, from the United States, and from Canada, and then deliver either directly into France, or first into British ports, and then from Britain into France. To beat the German Army is ultimately a problem in sea communications. The whole of these have to pass through the bottle-neck of the Western end of the Atlantic lanes. Into an area south of Ireland and north of Ushant, a hundred miles square, every ship that comes from the Mediterranean, from the Cape, from Buenos Ayres, Rio, the West Indies, or the Gulf of Mexico, from the Atlantic seaboard of America, must come.
Secondary only to this are the areas that feed ships into it, or into which the ships that pass through it are dissipated on their way to the several ports—the Mediterranean, the Bay of Biscay, the English Channel, St. George’s Channel, the Irish Sea. It is in these, when it is driven from the main funnel point of traffic, that the submarine must do its work. The defeat of the submarine, when at large, turns upon three factors: (1) the under-water offensive—that is, mine-fields, that will tend to keep it within certain areas; (2) the efficiency with which ships liable to attack are protected by convoy; and (3) the skill and persistence with which submarines, once on their hunting grounds, are in turn hunted. To maintain a cross-Channel barrage, the enemy surface craft must be handicapped in every possible way. The second and third factors of anti-submarine war make heavy demands on material, on personnel, and on skill, judgment, and organization. Here the decisive material factor is the number of destroyers available for both forms of work. When it comes to a close-quarters fight, no craft that has a speed of less than thirty knots, that cannot maintain itself in any weather, that does not possess a large cruising radius, can be of the first efficiency. The larger petrol-driven submarine-chasers and the many special craft which are built for various purposes in connection with the defensive campaign, all have their field of utility. But for the final power to rush swiftly on to a submarine if it is momentarily seen afloat, and for covering the area into which it can submerge itself, while the destroyer approaches with depth bombs, the destroyer, if only from its superior speed, stands supreme as the enemy of the U-boat. From the very earliest days of the submarine work it has, then, been axiomatic that every measure which will put a larger number of destroyers at our disposal should be taken at almost any cost. How does the work at Zeebrügge and Ostend help us, both in this respect and in a mining policy?
At these two ports our enemy was able to maintain a very considerable destroyer force. Its activities were necessarily mainly confined to work in darkness or in thick weather. But in such conditions its efficiency was of a very high order. The public only heard of its activities when it shelled some point of the coast of Kent, or raided our trawlers or other patrols, and, in all conscience, it heard of these activities often enough. Yet we were inclined to suppose them unimportant because their material results were insignificant. The news that a cross-Channel barrage was in course of establishment gave them a new value. But their value to the enemy should not be measured by the casualties they inflicted on our light craft, nor by their occasional excursions into the murder of civilians on shore. It lay in the fact that the enemy’s force permanently withdrew from the anti-submarine campaign numerous destroyer leaders and destroyers which had to be maintained at Dover to cope with it. From Zeebrügge to Emden—the nearest German port—is, roughly, three hundred miles by sea, and it does not need elaborate argument to show that if Zeebrügge and Ostend are permanently out of action the problem of dealing with enemy craft in the narrow seas is totally and entirely changed. With these gone, the East Coast ports became the natural centres from which to command the waters between Great Britain and Holland. They are fifty miles nearer Emden than is Dunkirk. If any German destroyers got west and south of Dunkirk, and the news of their presence were cabled to an East Coast base, destroyers could get between the enemy and his ports without difficulty. Thus, enemy surface craft, based upon German ports, would practically be denied access to Flemish waters altogether, and this by the East Coast and not by the Dover forces. In other words, the Dover patrol forces would, by the closing of Ostend and Zeebrügge, be set free for the highly important work of aiding in the anti-submarine campaign—and there is certainly no naval need that is greater.
The strategical objective, therefore, which Admiral Keyes put before himself in his expedition was, so far as he could, to set back the enemy’s naval bases by no less than three hundred miles. Its importance as setting free new forces, both for the direct attack on submarines, and for saving the mine-layers from attack, cannot be exaggerated, for it was a step—and a great step—forward in making sure of the sea communications on which all depends. It must be conceded, then that the results Admiral Keyes had in view amply justify a very considerable expenditure both of material and men. Let us next ask ourselves what kind of material he chose, and how he proposed to use his forces with utmost economy and maximum tactical effect.
SIR ROGER KEYES’S TACTICS
The purposes of the expedition, as we have seen, were to block the exit of the canal at Zeebrügge and the entrance of the small, narrow harbour at Ostend with old cruisers filled with cement, the removal of which would be an operation of a lengthy and tedious kind. Incidentally, the plan was to effect the maximum destruction of war stores and equipment at Zeebrügge and to sink as many as possible of the enemy vessels found in either port, and finally, to inflict on the enemy the maximum possible losses of personnel. By blocking the canal the value of Zeebrügge was reduced from being an equipped base to being a mere refuge. As there were two points of attack, the expedition naturally resolved itself into two distinct, but simultaneous, undertakings. The simpler, the less dangerous, the less ambitious, but, as the event showed, the more difficult operation of the two, was the attempt to block Ostend. The larger, more complex, and infinitely more perilous undertaking, but because of its very complications, ultimately easier, was the attempt at Zeebrügge. In its broad outlines, the scheme was to get the ships as near as possible without detection, and then to trust to a final rush to gain the desired position. Concealment up to the last moment was to be secured by smoke screens. At Ostend the problem was simply to run two or three ships into the entrance—that is, to get them into position before the enemy’s artillery made it impossible to manœuvre. If the Ostend attempt failed, it was largely because a sudden change in the weather conditions robbed the smoke screens, which were to hide the ships, of their value, so that the operation of placing the block-ships accurately was made almost impossible. The operation of blocking such entrances has, of course, long been familiar. The exploit of Lieutenant Hobson in the Spanish-American War, is fresh in the memories of all sailors. This failed through the steering gear of the blocking-ship being destroyed by gunfire at the critical moment. The Japanese attempted the same thing on a large scale at Port Arthur but with anything but complete success. If the first Ostend effort, then, fell short of finality, we have the experience of these earlier precedents to explain and account for it.
I have dealt with Ostend first because, after the preliminary bombardment, nothing more could have been attempted than to force the ships into the harbour entrance and sink them there. But at Zeebrügge a far more intricate operation was possible. Zeebrügge is not a town. It is just the sea exit of the Bruges Canal, with its railway connections, round which a few streets of houses have clustered. The actual entrance to the canal is flanked by two short sea walls, at the end of each of which are guide lights. From these lights up the canal to the lock gates is about half a mile. A large mole protects the sea channel to the canal from being blocked by silted sand. The mole is connected to the mainland by five hundred yards of pile viaduct. The mole is nearly a mile long, built in a curve, a segment amounting to, perhaps, one-sixth of a circle, the centre of which would be a quarter of a mile east of the canal entrance, while its radius would be three-quarters of a mile. It is a large and substantial stone structure, on which are railway lines and a railway station, and has been turned to capital military account by the enemy, who erected on it aircraft sheds and military establishments of many kinds.
The general plan was to bombard the place for an hour by monitors and, under cover of this fire, for the attacking squadron to advance to the harbour mouth. Then, when the bombardment ceased, Vindictive was to run alongside the mole, disembark her own landing party and those from Iris and Daffodil, who were to overpower the enemy protecting the guns and stores while the old submarines were run into the pile viaduct to cut the mole off from the mainland, thus isolating it. Meanwhile, other forces were to engage any enemy destroyers or submarines that might be in the port. Finally, the block-ships were to be pushed right up into the canal mouth and there sunk. The success of the latter part of these operations turned upon the extent to which the enemy could be made to believe that the attack on the mole was the chief objective.