Over and above the considerations already noticed, there are three others, all of which favour the security of our trade by permitting a much more extended choice of route.  The first is, that steam vessels are not forced by prevailing winds to keep to particular courses.  The second is, that the improvements in the art of navigation no longer render it so necessary to make well-known landfalls during transit.  The third is, that the multiplication of our great ports of distribution have divided the old main flow of trade to the Channel into a number of minor streams that cover a much wider area and demand a greater distribution of force for effective attack.  It will be obvious that the combined effect of these considerations is to increase still further the chances of individual vessels evading the enemy’s cruisers and to lessen the risk of dispensing with escort.

Nor are the new practical difficulties of sporadic operations on the great routes the only arguments that minimise the value of convoys.  We have also to remember that while the number of vessels trading across the ocean has enormously increased since 1815, it is scarcely possible, even if the abolition of privateering prove abortive, that the number of cruisers available for pelagic attack could exceed, or even equal, the number employed in sailing days.  This consideration, then, must also be thrown into the scale against convoys; for it is certain that the amount of serious operative damage which an enemy can do to our trade by pelagic operation is mainly determined by the ratio which his available cruiser strength bears to the volume of that trade.  This aspect of the question is, however, part of a much wider one, which concerns the relation which the volume of our trade bears to the difficulty of its defence, and this must be considered later.

It remains, first, to deal with the final link in the old system of defence.  The statement that the great routes were left undefended will seem to be in opposition to a prevailing impression derived from the fact that frigates are constantly mentioned as being “on a cruise.”  The assumption is that they in effect patrolled the great routes.  But this was not so, nor did they rove the sea at will.  They constituted a definite and necessary part of the system.  Though that system was founded on a distinction between defended terminals and undefended routes, which was a real strategical distinction, it was impossible to draw an actual line where the one sphere began and the other ended.  Outside the regularly defended areas lay a region which, as the routes began to converge, was comparatively fertile.  In this region enemies’ cruisers and their larger privateers found the mean between risk and profit.  Here too convoys, as they entered the zone, were in their greatest danger for fear of their escorts being overpowered by raiding squadrons.  Consequently it was the practice, when the approach of convoys was expected, to throw forward from the defended area