Organization. We know that the disposition of an assaulting unit is in the form of successive echelons, called waves. In order to protect these waves before the assault, it is necessary to construct for them trenches parallel to the enemy’s first line; and for this reason these are called parallels of departure. The trace of the first parallel fixes the directions of the others behind. For example, an assaulting battalion which is going to advance in four waves, might have two parallels of departure with two waves in each parallel. These parallels are narrow trenches like the defensive lines, but with a series of steps in the front side so that the men can go over the top easily. If there are no steps, trench ladders or footholds must be used.
Theoretically, one might think that the distance between these successive parallels should be the same as that between the attacking lines. But this is not practicable. Such practice would mark out boldly on the ground, for the enemy’s air observation, your intentions and your dispositions for the attack. Therefore, this method is strictly prohibited. Besides, it is not necessary, since the regulation distances between the lines and waves are not realized from the point of departure of the assault. The object of the assaulting companies is to cross “No Man’s Land” as quickly as possible to avoid the enemy’s defensive barrage and machine gun fire. Consequently, when the different lines of the first wave jump out of the same parallel of departure, they will dash across to the enemy’s first line with little regard to distances but with a fixed idea of reaching their first objective before the hostile garrison, and before the enemy’s barrage intervenes. They attain their regulation distance as soon as the zone of barrage is passed and when they have arrived at and crossed the first hostile line.
In order not to print the attack on the ground, so to speak, these different parallels of departure are not constructed in front of your position unless absolutely necessary. They are constructed when the distance across “No Man’s Land” is more than five hundred yards, when there is natural cover, such as woods to conceal them, and sometimes on reverse slopes. The different defensive lines of the sector make very convenient parallels of departure. The first waves of the assaulting company are placed in the firing and cover trenches of the first line. The reinforcing platoons are disposed in the transversal and intermediate and support lines. Behind these lines are constructed places d’armes or assembling places for the reserve troops. These places d’armes consist of a series of short transversal trenches leading off both sides of a central boyau.
If the first hostile line is too far from our own first line, on the night previous to the attack, hasty parallels of departure are constructed out in “No Man’s Land” for the leading wave of the assault. This is to give this leading element the best possible chance to arrive at the enemy’s first line uninterrupted by artillery fire and before the hostile garrison.
The work of preparing the ground for the disposition of the attacking troops also comprehends the following:
Several boyaux.
Command posts and observatories in advance of those of the defensive sector. Each chief must now be in the middle of his unit and not behind it.
Depots and medical aid stations. Each company has its own little ammunition depot near the post of the captain.
Ditches for telephone wires. Each battalion has telephone wires brought up in its main boyau as far as the first parallel. At this point, telephone material is stored so that the system can be carried into the enemy’s position with the least delay.
Small bridges are constructed for the passage of the parallels by the reserves.