The Australian Victories in France in 1918

by Sir John Monash

It was clearly desirable both to deprive a besieger of such vantage ground, and also to provide the canal defences with a stout outpost defence. For these reasons, the Germans had constructed an elaborate system of trenches on a line generally parallel to and on the average a full mile west of the canal. These trenches had been perfected with dug-outs, concrete machine gun and mortar emplacements, and underground shelters. They were protected by belt after belt of barbed wire entanglements, in a fashion which no one understood better, or achieved more thoroughly, than the Germans.

But much more remained. Deep communication trenches led back to the canal banks, in the sides of which tier upon tier of comfortable living quarters for the troops had been tunnelled out. Here support and reserve troops could live in safety and defy our heaviest bombardments. They could be secretly hurried to the front trenches whenever danger threatened.

There was, indeed, a perfect tangle of underground shelters and passages. Roomy dug-outs were provided with tunnelled ways which led to cunningly hidden machine-gun posts, and the best of care was taken to provide numerous exits, so that the occupants should not be imprisoned by the blocking of one or other of them by our bombardment. But it was the barbed wire which formed the groundwork of the defence. It was everywhere, and ran in all directions, cleverly disposed so as to herd the attackers into the very jaws of the machine guns.

The stretch of 6,000 yards of the canal which had been tunnelled was, however, both a hindrance and a benefit to the perfection of the scheme. On the one hand, the advantage of the open cut, as a last obstacle, was lost. Its place had to be taken by a second complete system of trench and wire defences, roughly following the line of the tunnel, but of course far above the latter. On the other hand, the tunnel itself afforded secure living accommodation for a substantial garrison.

The Germans had collected large numbers of canal barges, and had towed them into the interior of the tunnel, mooring them end to end. They served as living quarters and as depots for stores and munitions. It was no great business to provide electric lighting for the tunnel. Indeed, the leads for this purpose had been in existence before the war. Here, again, underground shafts and ways were cut to enable the troops rapidly to man the trenches and machine guns, and as rapidly to seek a safe asylum from the heaviest shell fire.

The whole scheme produced, in fact, a veritable fortress—not one, in the popular acceptation of the term, consisting of massive walls and battlements, which, as was proved in the early days of the war at Liége and Namur, can speedily be blown to pieces by modern heavy artillery—but one defying destruction by any powers of gunnery, and presenting the most formidable difficulties to the bravest of Infantry.

Even this was not all. On the east side of the St. Quentin Canal and parallel to it were built still two further trench lines, both fully protected by wire entanglements, and capable of determined defence. The first of these is the Le Catelet line, about one mile distant from the canal. It skirts and embraces the villages of Nauroy and Le Catelet, while two miles still further east is the Beaurevoir line, the last or most easterly of all the prepared defences which the Germans had in France.

Neither of these latter trench systems was nearly so formidably prepared as the main systems previously described, but together with them they go to make up the whole Hindenburg defensive system. In this region that system runs generally due north and south, with many minor convolutions in its line. It is altogether some 4½ miles across from west to east.

As its overthrow could not be attempted in a single operation, it is necessary for clearness of description to give definite names to each of the successive lines of trenches which go to form the whole defence system. Taking them in the order in which we attacked them, from west to east, they will be referred to as:

The Hindenburg Outpost line (known also in this part of the field as the Hargicourt line).
The Hindenburg main line (i.e., the Canal and Tunnel line).
The Le Catelet line.
The Beaurevoir line.