by bombing the enemy trenches. For every German bomb that is dropped by
aeroplane on or behind the British lines, about twenty go down on
the heads of the Germans. British air bombs upon guns, stores and
communications do some of the work that the French effect by their
systematic demolition fire.

And the British aviator has discovered and is rapidly developing an
altogether fresh branch of air activity in the machine-gun attack at a
very low altitude. Originally I believe this was tried in western Egypt,
but now it is being increasingly used upon the British front in France.
An aeroplane which comes down suddenly, travelling very rapidly, to
a few hundred feet, is quite hard to hit, even if it is not squirting
bullets from a machine gun as it advances. Against infantry in the open
this sort of thing is extremely demoralising. It is a method of attack
still in its infancy, but there are great possibilities for it in the
future, when the bending and cracking German line gives, as ultimately
it must give if this offensive does not relax. If the Allies persist in
their pressure upon the western front, if there is no relaxation in the
supply of munitions from Britain and no lapse into tactical stupidity, a
German retreat eastward is inevitable.

Now a cavalry pursuit alone may easily come upon disaster, cavalry can
be so easily held up by wire and a few machine guns. I think the Germans
have reckoned on that and on automobiles, probably only the decay of
their _morale_ prevents their opening their lines now on the chance of
the British attempting some such folly as a big cavalry advance, but
I do not think the Germans have reckoned on the use of machine guns in
aeroplanes, supported by and supporting cavalry or automobiles. At the
present time I should imagine there is no more perplexing consideration
amidst the many perplexities of the German military intelligence than