of the British shells; the hasty deployment of
the German cavalry; the further "holding up" of the main-guard of the
Advanced Guard while a reconnaissance was being carried out with the
help, perhaps, of a "Taube." Remember that the Germans must have been
daily, almost hourly, expecting the Allies to make a determined attempt
to check their continued advance, and must have been very nervous of
walking into some trap. Therefore the Commander of the German Advanced
Guard would have to discover very exactly the nature of the resistance
in front of him before the Officer commanding the main body--some miles
behind, of course--could decide what force it would be necessary to
deploy in order to dislodge the enemy from his position.

This is no easy matter. What the retreating army is fighting for is
time--time to get clean away. Consequently, if the Officer commanding
the advancing army deploys a larger force than is necessary, he grants
his opponent the very thing that he wants--time, since the deployment
of, say, a Division is a very lengthy operation, occupying at least
three hours. On the other hand, if he details too small a force for the
work, his attack is held in check, and more time than ever is wasted in
reinforcing it in a measure sufficient to press home the attack.

The Subaltern imagined the long wait while the shells shrieked over the
heads of the infantry towards an enemy as yet unseen. Then the enemy
shells would begin to feel their way to the thin brown line of trenches,
and under cover of their fire the infantry, now deployed into fighting
formations, would "advance." Then our men would begin firing, firing
with cool precision. The landscape would soon be dotted with grey ants.
Machine-guns would cut down whole lines of grey ants with their
"plop-plop-plop." Shrapnel would burst about whole clouds of grey ants,
burying them in brown clouds of dust. Finally, the directing brain would
decide that it was time to cut and run. The artillery fire would be
increased tenfold, and under cover of it the brown ants would scamper
from the trenches and disappear into the green depths of the woods. Soon
the firing would cease. The retreating party would have got safely,
cleanly away, having gained many precious hours for the main body, and
having incidentally inflicted severe losses on the enemy. The latter,
have nothing left to do but to re-form (thus losing still more time),
would then continue his pursuit weaker and