he
complete overthrow of the German intrenched positions at this point.

[Illustration: MAP: Arras in the Southwest corner, Douai in the
Northeast.]
THE FAMOUS HINDENBURG LINE THAT CRUMBLED IN 1918.

The Germans retreated hastily to the Canal du Nord, and on September 3d
Queant was captured by an advance on a twenty mile front, along with ten
thousand prisoners. The Allied forces were moving steadily forward. On
September 18th the British reached the defenses of Cambrai and were
encircling the city of St. Quentin. On October 3d the advance upon
Cambrai forced the Germans to evacuate the Lens coal fields, and on
October 9th another advance over a thirty-mile front enabled the Allies
to occupy Cambrai and St. Quentin. On the 11th they had reached the
suburbs of Douai. By this time the whole of the Picardy salient had been
wiped out.

The preceding summary of this great movement gives little idea of the
tremendous struggle which had gone on during these two critical months,
and hardly does more than suggest the tremendous importance of the
British operations. The Hindenburg line was like a great fortification,
and for more than a year had been regarded as impregnable. At Bullecourt
there were two main lines. One hundred and twenty-five yards in front of
the first line was a belt of wire twenty-five feet broad, so thick that
it could not be seen through. The line itself contained double
machine-gun emplacements of ferro-concrete, one hundred and twenty-five
yards apart, with lesser emplacements between them. More belts of wire
protected the support line. Here a continuous tunnel had been
constructed at a depth of over forty feet. Every thirty-five yards there
were exits with flights of forty-five steps. The tunnels were roofed
and lined and bottomed with heavy timber, and numerous rooms branched
off. They were lighted by electricity. Large nine-inch trench mortars
stood at the traverses and strong machine-gun positions covered the line
from behind.

The Hindenburg line was really only one of a series of twenty lines,
each connected with the others by communicating trenches. The main lines
were solid concrete, separated by an unending vista of wire
entanglements. At points this barrier barbed wire extended in solid
formation for ten miles. This tremendous system of defenses was
originally called by the Germans the Siegfried line, and in the spring
of 1917 they found it wise, at points where a strong offensive was