amous series of flanking movements which
finally reached the sea.

It was their success in driving the German army to earth when it was
stronger than they were that saved the Allies, and gave them the
breathing time required in which to further their preparations and train
new troops, and likewise it is this same mode of trench warfare which
has made their task so difficult when they have taken the offensive.

Against ordinary trench lines, as known in the early stages of the war,
the French field pieces were more effective than the heavy cannon of the
Teutons, just as they had been in the open. Shooting in flat trajectory
across the trench, and exploding just above it, the shrapnel scattered
more death downward than the heavy projectile could scatter upward after
it had buried itself in the soft earth.

But with the continuous line of trenches stretching from Switzerland to
the sea, with consequent impossibility of out-flanking, demonstrated by
the Germans to their sorrow in repeated repulses of their drives to cut
through to Calais, each side felt justified in replying to the artillery
of the other by digging deeper and more permanently, with many feet of
shelter overhead. This ended the effectiveness of shrapnel except for
the repulse of attacks, and again the heavy guns swung into the position
of pre-eminence.

A SITUATION ALMOST BEYOND CONTROL.

It was at this stage, however, that both sides realized how totally
inadequate the supply of these heavy guns and ammunition was to cope
with the situation. While the heavy gun was more effective in blasting
out the enemy from his dugouts than the field piece, it required many
times the artillery power which either side possessed to handle the job.

Then commenced the race of the ammunition and gun factories to turn out
their products by the ton where they had been turned out by the pound
before; a race in which the Allies took and held the lead.

With the greatly increased number of heavy guns it became possible to
develop the famous curtain of barrage fire, also known as drum fire,
with this type of ordnance, as well as with shrapnel.

It is with this form of attack that the Allies blasted their way slowly
but steadily through the strongest networks of trenches which the
Germans were able to build.

Along a given section of the front, or rather just behind it, the guns
were placed singly or in pairs, widely scattered, some close to the line
and some well back