In the past a military occupation of the hostile country has generally been the ultimate method of bringing to bear this pressure on the spirit, and may still be necessary against semi-civilized peoples spread out in little self-supporting communities, whose material wants are simple, and who offer no highly organized industrial and economic system for attack or control by an enemy. But though the indignity and restrictions that arise from a military occupation are always galling, the conscience of the world forbids, or at least limits, the terrorism of earlier times and so makes the mere presence of an invading army less irksome. Conversely, with the growth of civilization the dislocation or control of an enemy’s industrial centres and communications becomes both more effective and more easy as the means by which to subdue his will to resist. Every modern industrial nation has its vitals; in one case it may be essential mining areas, in another manufacturing districts, a third may be dependent on overseas trade coming into its ports, a fourth so highly centralized that its capital is the real as well as the nominal heart of its life. In most cases there is a blend of these several factors, and in all the regular flow of transport along its arteries is a vital requirement. As warships are tied to the sea, they cannot penetrate into an enemy country; as, moreover, they are notoriously at a disadvantage against land defences, they cannot even occupy his ports. Hence they are limited to indirect action against the enemy’s vitals――either by blockade, by enabling troops to be landed, or nowadays by serving as a mobile base for aircraft which can strike at “nerve centres” within some 250 miles of the coast. Armies have hitherto been the means of “direct action,” whether against the resources of the enemy nation, the intimidation of the people, or by the capture or overthrow of individuals who were the mainspring of the opposing policy. Armies, however, suffer one serious handicap in subduing the hostile will. Being tied to one plane of movement, compelled to move across the land, it has rarely been possible for them to reach the enemy capital or other vital centres without first disposing of the enemy’s main army, which forms the shield of the opposing government and nation. It was because of this age-long limitation that the short-sighted, if natural, delusion arose that the armed forces themselves were the real objective.