outside the angle, as from the arrows NNN; (3) containing within
itself, protected by its ring of fortifications, passages, PP, for
traversing the two natural obstacles, γβ and βδ, which meet at the
point β.

[Illustration: Sketch 38.]

There you have the elements of the position in which the advance
corner of the great French square was situated just before it took the
shock of the main German armies. The two lines AB and BC are the
French and British armies lying behind the Sambre, γβ, and the Middle
Meuse, βδ, respectively; but the line of the Sambre ceases to protect
eastward along the dotted line αγ beyond the point up to which the
river forms a natural obstacle, while from K to B the line is
protected by the river Sambre itself. The more formidable obstacle,
βδ, represents the great trench or ravine of the Meuse which stretches
south from Namur. The town of Namur itself is at B, the junction of
the two rivers; and the fortified zone, SSS, is the ring of forts
lying far out all round Namur; while the passages, PP, over the
obstacles contained within that fortified zone, and accessible to the
people _inside_ the angle from M, but not to the people _outside_ the
angle from NNN, are the bridges across both the Sambre and the Meuse
at Namur.

All this is, of course, put merely diagrammatically, and a diagram is
something very distant from reality. The "open strategic square" in
practice comes to mean little more than two main elements--one the
operative corner, the other a number of separate units disposed in all
sorts of different places behind, and generally denominated "the
manoeuvring mass." If you had looked down from above at all the French