On the following sketch map, Belgium, Alsace-Lorraine, East Prussia, and Silesia are shaded, as were the four corners of the diagram.  No. 1 is Belgium, 2 is East Prussia, 3 is Alsace-Lorraine, 4 is Silesia.  The area occupied by the German Empire, including its present occupation of Belgium, is marked by the broad outline; and the areas shaded represent, not the exact limits of the four territories that are so important, but those portions of them which are essential:  the non-Polish portion of Silesia, the non-Polish portion of East Prussia, the plain of Belgium, and all Alsace-Lorraine.

[Illustration:  Sketch 13.]

Now the reason that each of these must at all costs be preserved from invasion is, as I have said, different in each case, and we shall do well to examine what those reasons are; for upon them depends the political hesitation they inevitably, cause to arise in the plans of the Great General Staff.

1. Belgium. The military annexation of Belgium has been a result of the war, and, from the German point of view, an unexpected result.  Germany both hoped and expected that her armies would pass through Belgium as they did, in fact, pass through Luxembourg.  The resistance of Belgium produced the military annexation of that country; the reign of terror exercised therein has immobilized about 100,000 of the German troops who would otherwise be free for the front; the checking of the advance into France has turned the German general political objective against England, and, to put the matter in the vaguest but most fundamental terms, the German mind has gradually come, since October, to regard the retention of Belgium as something quite essential.  And this because:—­(a) It gives a most weighty asset in the bargaining for peace. (b) It gives a seaboard against England. (c) It provides ample munition, house-room, and transport facility, without which the campaign in North-eastern France could hardly be prolonged. (d) It puts Holland at the mercy of Germany, for she can, by retaining Belgium, strangle Dutch trade, if she chooses to divert her carriage of goods through Belgian ports. (e) It is a specific conquest; the Government will be able to say to the German people, “It is true we had to give up this or that, but Belgium is a definite new territory, the occupation of which and the proposed annexation of which is a proof of victory.” (f) The retention of Belgium has been particularly laid down as the cause of quarrel between Great Britain and Germany; to retain Belgium is to mark that score against what is now the special enemy of Germany in the German mind. (g) Antwerp is the natural port for all the centre of Europe in commerce westward over the ocean. (h) With Belgium may go the Belgian colonies—­that is, the Congo—­for the possession of which Germany has worked ceaselessly year in and year out during the last fifteen years by a steady and highly subsidized propaganda against the Belgian administration.  She has done it through conscious and unconscious agents; by playing upon the cupidity of French and British Parliamentarians, of rum shippers, upon religious differences, and upon every agency to her hand.