and constructed rapidly under the conditions of the campaign. Such
works dotted round the area you desire to defend are quite a different
thing to reduce from isolated, restricted, permanent forts. In the
first place, the enemy does not know where they are; in the second
place, you can make new ones at short notice; in the third place, if a
howitzer does spot your heavy gun, you can move it or its neighbours
to a new position; in the fourth place, the circumference you are
defending is much larger, and the corresponding area that the
besiegers have to search with their fire more extended. Thus, in the
old forts round Verdun, about a dozen permanent works absolutely fixed
and ascertainable upon the map, and covering altogether but a few
acres, constituted the defence of the town. Before September was out
the heavy guns had been moved to trenches far advanced into the field
to the north and east, temporary rails had been laid down to permit
their lateral movement--that is, to let them shift from a place where
they had perhaps been spotted to a new place, under cover of darkness,
and the sectors thus thrown out in front of the old fortifications in
this improvised mobile fashion were at least three times as long as
the line made by the ring of old forts, while the area that had to be
searched was perhaps a hundred times as large. For in the place of the
narrowly restricted permanent fort, with, say, ten heavy guns, you had
those same ten heavy guns dotted here and there in trenches rapidly
established in half a dozen separate, unknown, and concealed spots,
along perhaps a mile of wooded hill, and free to operate when moved
over perhaps double that front.

IV. _In Grand Strategy a German general theory of strategics was
opposed to a French general theory of strategics, and upon which of
the two should prove right depended, much more than on any of the
previous points, the ultimate issue of the campaign._