purposes of strategical thought it should be given a somewhat wider extension? Regarded from the point of view of human mobility, and of the different modes of mobility, it is evident that since land-power can to-day close the Black Sea, the whole basin of that sea must be regarded as of the Heartland. Only the Bavarian Danube, of very little value for navigation, may be treated as lying outside.
One more circumstance remains to be added, and we shall have before us the whole conception of the Heartland as it emerges from the facts of geography and history. The Baltic is a sea which can now be 'closed' by land-power. The fact that the German Fleet at Kiel was responsible for the mines and submarines which kept the Allied squadrons from entering the Baltic does not, of course, in any way vitiate the statement that the closing was by land-power; the Allied Armies in France were there by virtue of sea-power, and the German sea defences of the Baltic were there as a result of land-power. It is of prime importance in regard to any terms of peace which are to guarantee us against future war that we should recognise that under the conditions of to-day, as was admitted by responsible Ministers in the House of Commons, the
