‘Strategy,’ says the ‘EncyclopÆdia Britannica,’ ‘has been curtly described as the art of concentrating an effective fighting force at a given place at a given time, and tactics as the art of using it when there.’ In less scientific language, you fight a battle by means of tactics, and a campaign by means of strategy. But when nations live, as we have all been living for many years past, in constant preparation for war, there must be forethought as to the means and methods to be employed. Each nation has broad general plans, ready for the moment when fighting is decided upon, and ships, guns, and armies are provided accordingly. This is what is meant by war policy; and examples will come to mind at once. We live in a group of islands, with Dominions and other possessions overseas, and we have no desire to attack our continental neighbours. British war policy has therefore always been chiefly directed to the provision of an invincible navy for defending our shores and our commerce. The German Empire, on the other hand, is practically self-contained; it lies on the Continent, with land powers for neighbours whom it has long hoped and intended to dominate. German war policy, therefore, concerned itself until quite recently with plans for aggression by land, and only provided a powerful fleet when it became desirable to have a weapon in hand against England—not necessarily to fight us on equal terms, but, as they said themselves, to make us hesitate to take sides against them.

In this way it came about that both countries had a great naval war policy, and watched each other carefully, building dreadnoughts against dreadnoughts, and cruisers against cruisers. We made great and successful efforts to keep the lead; for sea power is a matter of life and death to us; and the Germans were spending every mark they could spare, to get more and more nearly upon even terms. It is certain that the war policy of both Powers took account of the possible uses of submarine boats; but the lines of thought which they followed were in some ways widely different, and they led, when war came, to unexpected developments. Let us consider for a few moments what the British admirals on the one hand, and the German on the other, intended to do with their submarine forces, and what they actually did when the time for action came.

British war policy was essentially non-aggressive. The Navy had but one possible antagonist of the first rank at sea, and that one we should never have fought with, except in a war of defence. Our submarines, therefore, had two obvious duties marked out for them. They would help in coast defence by making it dangerous for ships of war or transports to approach, and they might be used, if an opportunity arose, to attack a fleet in harbour, or a cruiser at sea. There was every probability that any fleet of a Power at war with us would sooner or later have to spend a good deal of time in port, and it would certainly be well to have the means to attack it there. But, important as this function was, the idea of defence against invasion probably came first, and there is no doubt that an efficient submarine force is a very formidable addition to our flotilla for coast defence. Perhaps we thought, in those years of perpetual preparation, too much about the ‘Invasion of England’ and too little about the duty of supporting our Allies on land; and we had this much justification, that the Power from which we had every reason to expect an attack, was one directed by men of great energy and determination, certain to be relentless in pressing a war home upon us, even at the risk of a heavy loss. On the other hand, those who spoke and wrote most about invasion, nearly always failed to realise the immense difficulty of the undertaking; and they failed especially to see that, in modern times, the conditions had changed very considerably in favour of the defence. The initial problem of an invader by sea must always be the provision of transport sufficient for a large body of troops, with arms, equipment, and supplies of food and munitions. Even if we allow only two tons of shipping per man—the Japanese allowed six tons—the transport of 100,000 men would take twenty vessels of 10,000 tons each, and to collect these and load them would be a big operation; difficult to conceal. In fact to conceal it, for a sufficiently long time, from a defence force well supplied with wireless telegraphy, fast scouts, and aerial observation, would now be a practical impossibility. But even if we suppose such an expedition to be able (under cover of fog, or by a complete surprise) to cross the North Sea unobserved, there remains the further difficulty of the landing. A place must be found where the invaders could obtain immediate control of supplies and communications; there are but half a dozen such places at most upon our eastern coast-line, and these are all prepared for a strenuous defence by land. If we add to the land defence a mine-field and the presence of an unknown number of submarines, the attempt becomes one involving the certainty of immense losses, and the extreme probability of failure. Even the German war-lords have not yet made up their minds to the risk of seeing eight or ten divisions drowned in an hour.

Besides coast defence and harbour attack, there might possibly be a chance for our submarines in a fleet action. Of that, all that can be said now is that our Submarine Service is believed to have shown greater promptness and ingenuity in its preparations than the German Admiralty, and awaits the next naval engagement with eager anticipation. But already it has been found practicable to use our submarines for two very important kinds of work, to an extent which was certainly quite unforeseen. One of these is the chase and destruction of enemy submarines—a kind of service which has been pronounced impossible, even in books written during the later stages of the War, but actual examples of which will be given in one of the chapters which describe our hunting methods. The other kind of work is the blockade of the enemy’s shipping trade and supply service, to be described when we come to the account of our submarine campaigns in the Baltic and Dardanelles.

If we turn now to German naval policy, we shall come at once upon an interesting point, which has not been generally understood. We have been told that the German Admiralty, before the War, was completely deceived as to the value of the submarine. And Mr. Marley Hay has been often quoted as saying that, in several conversations in 1911, Admiral von Tirpitz ‘expressed emphatically his opinion that he considered submarines to be in an experimental stage, of doubtful utility, and that the German Government was not at all convinced that they would form an essential or a conspicuous part of their future naval programme.’ Mr. Hay shows clearly that this was not said with the object of misleading; for he was urging Tirpitz to build, and the Admiral continued to refuse. When war broke out, the German Navy had only twenty-seven submarines built against seventy-six British and seventy French boats, and she was only building twelve more, against the twenty and twenty-three on our side. This may have been partly due to a miscalculation of their efficiency; but the main reason was probably that the directors of German war policy were (at that time) preparing for a war in which our Navy was to take no part. The account with England was to be settled at a later date. The immediate intention was to deal with France and Russia, and the assistance of the Austrian and Italian submarines in the Mediterranean was of course reckoned upon.

When war came these calculations were falsified. The German High Seas Fleet found itself unable to stand up to ours, and German war policy was forced to take a different direction. The U-boats’ first allotted task was the legitimate one of reducing our margin of superiority in battle-ships and cruisers. While our Fleet was certain to keep the sea, and protect our long coast-line and huge merchant tonnage, the German High Seas Fleet must lie in the Kiel Canal, risking only furtive and futile rushes into the open. But if the U-boats could hit a sufficient number of our more active war-ships, they might bring the forces nearer to an equality, and perhaps establish a prestige for their own Service. How they failed in this attempt we shall see presently.

When their failure in the game of attrition became evident, the U-boats were utilised in a different way. A submarine blockade of the British Isles was plainly threatened by Admiral von Tirpitz towards the end of 1914; and the official announcement of it was made on February 4, 1915. By this document it was declared that on and after February 18, every British or French merchant vessel found in the waters of the ‘war region’ round these islands ‘will be destroyed, without its always being possible to warn the crews or passengers of the dangers threatening.’ Neutral ships, it was added, would not be attacked unless by mistake; but they are warned not to take the risk.

Those who know even a little of the history of our old wars will see at a glance that this is a new move in naval war policy, and one made by the Germans to get over certain difficulties which arise from the very nature of submarine boats, and which are especially embarrassing when the submarines belong to a navy decidedly inferior to its enemies at sea. The old and well-established rules of naval war laid down that you could only interfere with merchant shipping if it were engaged in carrying contraband of war. To ascertain whether the ship you had sighted was carrying contraband or not, you had to board and search her. If innocent, you must let her proceed on her voyage. If apparently guilty, you took over her men or otherwise placed them in safety, put a prize crew on board and sent her home to a port of your own, to be tried legally by a properly constituted tribunal called a Prize Court. If this Court decided that she was, in fact, carrying contraband, she was your prize. If you were forced by stress of circumstances to destroy the prize, instead of sending her into port, you took every care to remove everyone on board before doing so; and when you had not room for so many people, you released the prize rather than endanger or sacrifice the lives of non-combatants.

All these humane rules could well be observed by any ordinary cruiser; and they were, in fact, kept by the Emden and other German cruisers when harrying British commerce in the East. But it is obvious at the first glance that a submarine would be continually in difficulties over them. It would always be risky for so fragile and unhandy a vessel to board and search a big ship, which might prove to be armed with guns or bombs. No submarine could find room for merchant crews or passengers in her own small compartments, and no submarine could afford to spare a prize crew for even one prize, or the time and horse-power to tow her into port. In short, it was plain, from the first, that the legitimate cruiser game could not be played at all by submarine boats. The Government of the United States put the truth unanswerably in these words: ‘The employment of submarines for the destruction of enemy trade is of necessity completely irreconcilable with the principles of humanity, with the long existing undisputed rights of neutrals, and with the sacred privileges of non-combatants.’

The British Navy had an advantage here—the inestimable advantage of a force that could keep the sea against all its enemies. It was, therefore, possible for our submarines to stop an occasional ship with impunity, or to call up a destroyer and send a prize into port; and in the narrow waters of the Baltic and the Sea of Marmora, supply ships and merchantmen were captured and destroyed by them with every regard for the laws of humanity. But the German submarines had no fleet at sea to back their attempted blockade, and German war policy therefore took the downward course, hacking a way through the rules, and sacrificing, for the hope of victory, the very foundations of civilised human life. The U-boats began by turning passengers and crews adrift in open boats, no matter in what weather or how far from land. They went on to sink even great liners without search, and without warning; and they came finally down to the destruction of helpless men and women in boats, in order that the ships they had torpedoed might disappear without a trace—spÜrlos versenkt.