The grenadier squad proceed to their work of clearing the fire and communication trenches.
The Second Wave
The second wave of the first line starts forward at the moment the first wave reaches the hostile trenches. If it starts sooner, it will unite with the first at the entanglement and become involved in the fight for the fire trench. It will be broken up prematurely and will be unable to take advantage of the developments of the fight of the first wave. The reinforcement by the second wave and the disorganization produced by the assault lead to a mixture of units in the trenches of the first position. Before starting out to the assault of the next trench it is necessary that order be restored. When this is accomplished the attack is launched against the second line. In front of the supporting points the combat rages. The men are barely able to hold on the outer edges. In the interval the advance has reached high tide and has expanded like a wave and stopped. This is the limit that can be expected of the first line.
Hasty cover is prepared and advantage taken of such cover as may exist. All elements of the attack open fire on the second position.
The Second Line
Under the cover of these operations the second line has come up in a series of three lines, where it is built up compact at the position of the stopped first line. From this point its attack against the enemy's second line is launched. The lines are worked up to a point from which the assault is to be made, and when the time comes the first wave dashes out to the attack, followed by the second wave in the same manner as the assault against the first position was made.
The action of the two lines of attack may be expected to overwhelm the greater part of the two main hostile positions. At certain points, however, the resistance will hold out, and, if not overcome, will constitute points of support to which the enemy may bring up reinforcements and even turn the tide of battle by a counter attack.
To deal with these points that hold out, as well as with hostile reinforcements which may arrive, the reserve is launched into action, which brings the attack into the open ground beyond the second line of defense, and maneuver operations are begun. The mobile units are rapidly thrown into action, and large forces from the general reserve are hurried to the point where the lines of defense are broken through.
From what has gone before we may deduce that the following conditions must prevail to attain success in an attack on a prepared position:
1. The attack must be planned down to the most minute detail.