plane, which is of a boomerang nature, a weapon of land-power as against sea-power. Modern artillery, moreover, is very formidable against ships. In short, a great military power in possession of the Heartland and of Arabia could take easy possession of the cross-ways of the world at Suez. Sea-power would have found it very difficult to hold the Canal if a fleet of submarines had been based from the beginning of the war on the Black Sea. We have defeated the danger on this occasion, but the facts of geography remain, and offer ever-increasing strategical opportunities to land-power as against sea-power.
It is evident that the Heartland is as real a physical fact within the World-Island as is the World-Island itself within the Ocean, although its boundaries are not quite so clearly defined. Not until about a hundred years ago, however, was there available a base of man-power sufficient to begin to threaten the liberty of the world from within this citadel of the World-Island. No mere scraps of paper, even though they be the written constitution of a League of Nations, are under the conditions of to-day a sufficient guarantee that the Heartland will not again become the centre of a World- War. Now is the time, when the Nations are fluid, to {hws|con|consider}}
