The will to conquer is the first condition of victory. - Ferdinand Foch

The Rhineland question is controlled by the Rhine. The river is the deciding factor. The master of the Rhine is the master of the surrounding country. Whichever side does not control the Rhine has lost.

I proposed a solid basis for the new, post-war Europe: Germany permanently bounded on the west by the Rhine, and the Rhine held by a small Allied force; the creation of an independent Rhineland State separating France from Germany, similar to England's creation of Belgium. ... What had we in place of that plan? A scheme for a hypothetical and conditional alliance by which, at best, we could receive no immediate military protection; and a temporary occupation, the main drawback of which was its indecisiveness.

The truth is, no study is possible on the battlefield. One does there simply what one can in order to apply what one knows. Therefore, in order to do even a little, one has already to know a great deal, and to know it well.