d sweep his own trenches
should these be taken. The ground lent itself to good artillery
observation on the enemy's part, and he had skillfully arranged for
cross-fire by his guns.

[Sidenote: A composite system of great strength.]

These various systems of defense, with the fortified localities and
other supporting points between them, were cunningly sited to afford
each other mutual assistance and to admit of the utmost possible
development of enfilade and flanking fire by machine guns and artillery.
They formed, in short, not merely a series of successive lines, but one
composite system of enormous depth and strength.

[Sidenote: Many lines prepared in the rear.]

Behind this second system of trenches, in addition to woods, villages,
and other strong points prepared for defense, the enemy had several
other lines already completed; and we had learned from aeroplane
reconnoisance that he was hard at work improving and strengthening these
and digging fresh ones between them and still further back.

In the area above described, between the Somme and the Ancre, our
front-line trenches ran parallel and close to those of the enemy, but
below them. We had good direct observation on his front system of
trenches and on the various defenses sited on the slopes above us
between his first and second systems; but the second system itself, in
many places, could not be observed from the ground in our possession,
while, except from the air, nothing could be seen of his more distant
defenses.

[Sidenote: The lines of the Allies.]

North of the Ancre, where the opposing trenches ran transversely across
the main ridge, the enemy's defenses were equally elaborate and
formidable. So far as command of ground was concerned we were here
practically on level terms, but, partly as a result of this, our direct
observation over the ground held by the enemy was not so good as it was
further south. On portions of this front the opposing first-line
trenches were more widely separated from each other, while in the
valleys to the north were many hidden gun positions from which the enemy
could develop flanking fire on our troops as they advanced across the
open.

[Sidenote: Period of active operations.]

The period of active operations dealt with in this dispatch divides
itself roughly into three phases. The first phase opened with the attack
of July 1, 1916, the success of which evidently came as a surprise to
the enemy and caused conside