There remains only a third alternative. This is to assemble the invading military force at suitable ports as before, and to attempt to engage the attention of the defending naval force by operations at a distance for a time sufficient to secure the unmolested transit of the military expedition. This is the method which has nearly always been employed by an enemy projecting an invasion of this country. It has never yet succeeded, because it always leads in the end to a situation which is practically indistinguishable from that involved in the second alternative, which I have already discussed and excluded. The naval and the military elements in the enterprise of invasion being now, by the hypothesis, separated in space and for that reason incapable of being very exactly combined in time, a whole series of highly indeterminate factors is thereby introduced into the problem to be solved by the invader. There are elements of naval force, to wit, all manner of small craft, which are not required for the main conflict of fleets--and it is this conflict which alone can secure the command of the sea--but which are eminently adapted for the impeachment and destruction of unarmed transports. These will be employed in the blockade of the ports in which the military forces are collecting. If the assailant employs similar craft to drive the blockaders away, the defender will bring up larger craft to stiffen his blockading flotillas. The invading force will therefore still be impeded and impeached. The process thus goes on until, if it is not otherwise decided by the conflict of the main fleets at a distance, the contending naval forces of both sides are attracted to the scene of the proposed embarkation, there to fight it out in the conditions involved in the second alternative considered above, conditions which I have already shown to be the least favourable to the would-be invader. In a masterly analysis Mr Julian Corbett has shown that the British defence against a threatened invasion has always been conducted on these lines, that the primary objective of the defence has been the troops and their transports, and that the vigorous pursuit of this objective has always resulted in a decision being obtained as between the main fleets of the two belligerents. That the decision has always been in favour of the British arms is at once a lesson and a warning--a lesson that immunity from invasion can only be ensured by superiority at sea, a warning that such superiority can only be secured by the adequate preparation, the judicious disposition, and the skilful handling of the naval forces to be employed, as well as by an unflinching _animus pugnandi_. But no nation which goes to war can hope for more or be content with less than the opportunity of obtaining a decision in these conditions. The issue lies on the knees of the gods.