Secondly, the practical disappearance of the sailing ship from the seas has profoundly modified all the pre-existing conditions affecting the attack and defence of commerce afloat. In the days of sailing, all vessels were compelled to sail according to the wind, that is, to take devious courses whenever the wind was adverse, so that some of them might at all times be found scattered over very wide areas of the seas connecting the ports of departure with those of arrival. Accordingly the sporadic attack on commerce by isolated warships cruising at large within the limits of trade routes, which might be hundreds of miles in width, was often productive of very appreciable results. There were few blank coverts on the seas to be drawn. Nowadays a steamer can always take the most direct course to her destination. As a consequence, trade routes have now been narrowed down to what may more fittingly be called lines of communication, and these lines possess the true characteristic of all lines, namely, that they have practically no breadth. Thus the areas bounded by these lines are nowadays all blank coverts. Any one who happens to cross the Atlantic, as I have crossed it more than once, by one of the less frequented routes, will know that the number of vessels sighted in a voyage quite as long as any warship could take without coaling may often be counted on the fingers of one hand. Another characteristic of these lines is that though their points of departure and destination are fixed, yet the lines joining these points may be varied if necessary to such an extent that any warship hovering about their ordinary direction would be thrown entirely off the scent. On the other hand their ports of departure and destination being fixed, the lines of communication must inevitably converge as they approach these points. There are other points also more in the open at which several lines of communication may intersect. At these "terminal and focal points," as Mr Corbett has aptly called them, the belligerent, being by hypothesis inferior to his adversary, must needs endeavour to concentrate his attack on his enemy's commerce, because at any other points the game would not be worth the candle. But it is precisely at these points that the superior adversary will concentrate his defence, and being superior, will take care to do so in force sufficient for the purpose. So far as the remaining portions of the lines of communication need any direct defence at all this can be afforded, if and when necessary, by collecting the merchant ships about to traverse them into convoys and giving them an escort sufficiently powerful to deal effectually with attacks which from the nature of the case can only be sporadic and intermittent. Be it remembered that the last thing a warship bent on commerce destruction wants is to encounter an enemy in superior or even in equal force. The moment she does so her game is up.
Thirdly, the substitution of steam for sails has very largely reduced the enduring mobility of the commerce-destroying warship. In time of war no warship will ever go further from the nearest available supply of coal than is represented by considerably less than half of the distance that she can steam at full speed with her bunkers full. If she does so she runs the risk, if chased, of burning her last pound of coal before she has reached shelter. Coaling at sea is only possible in exceptional circumstances, and is in any case a very tedious operation. A warship which attempts it will be taken at a great disadvantage if an enemy catches her in the process. Colliers, moreover, are exposed to capture while proceeding to the appointed rendezvous, and if they fail to reach it the warship awaiting them will be placed in extreme danger. All these difficulties and dangers may be surmounted once and again, but they must needs put a tremendous handicap in the long run on the commerce-destroying efforts of a belligerent who is not superior to his adversary at sea. Of course if he is superior at sea the enemy's commerce will be at his mercy, and nothing can prevent its destruction or at least its total suppression. But that is not the hypothesis we are considering.
Fourthly, the power of the modern warship to send her prizes into court for adjudication, or to destroy them off-hand on capture is much more limited than was that of her sailing predecessor. If she sends them into port she must either put a prize crew on board or escort them herself. In the former case the prizes, and in the latter case both prizes and their captors are liable to recapture, a liability which becomes the greater in proportion as the enemy is superior at sea. As to the former alternative, moreover, the crew of a modern man-of-war is highly specialized, and in particular its engine-room complement, which must furnish a portion of every prize crew, is at the outset no greater than is required for the full fighting efficiency of the ship. It is probable, therefore, that the captor would in nearly all cases adopt the alternative of destroying his prizes at sea. In that case there will be no prize money for any one concerned, but that is perhaps a minor consideration. A far more important consideration is that before destroying the prize the captor must take its crew on board and provide food and accommodation for them. Any other course would be sheer piracy and would inevitably lead to drastic reprisals. Now, before the captor had destroyed many prizes in this fashion—especially if even one of them happened to be a passenger steamer well filled with passengers—she would find herself gravely embarrassed by the number of her prisoners, and the need of providing for them even in the roughest fashion. A captain having to fight his ship even with a few hundreds of prisoners on board would be in no very enviable position.
The foregoing are the leading considerations which appear to me to govern the problem of the attack and defence of maritime commerce in modern conditions of naval warfare. I have discussed the question in greater detail in a work entitled Nelson and Other Naval Studies, and as I have seen no reason to abandon or substantially to modify the conclusions there formulated, I reproduce them here for the sake of completeness:—
1. All experience shows that commerce-destroying never has been, and never can be, a primary object of naval war.
2. There is nothing in the changes which modern times have witnessed in the methods and appliances of naval warfare to suggest that the experience of former wars is no longer applicable.
3. Such experience as there is of modern war points to the same conclusion and enforces it.
4. The case of the "Alabama," rightly understood, does not disallow this conclusion but rather confirms it.
5. Though the volume of maritime commerce has vastly increased, the number of units of naval force capable of assailing it has decreased in far greater proportion.
6. Privateering is, and remains abolished, not merely by the fiat of International Law, but by changes in the methods and appliances of navigation and naval warfare which have rendered the privateer entirely obsolete.