CHAPTER IVTHE RELIEF
There are two kinds of reliefs, General and Interior reliefs.
AGeneral Reliefis one where a large unit, such as a division or an army corps, is relieved from its position on the front.
AnInterior Reliefis one where a small unit, such as a company, battalion, or regiment, is relieved from its area by another unit of the same division within the position.
A general relief takes place for the following reasons:
In order to send a unit far to the rear to good billets for complete rest and perhaps for recruiting.
To withdraw and gather together the units of a corps, for the purpose of training for an offensive.
To permit the strategical movement of large units along the entire front.
_Interior Relief in the Division_
General reliefs should not be made any oftener than necessary as they hinder methodical and continuous organization of the defense, observation of the enemy, and the preparation of contemplated offensives. It is for the express purpose of decreasing the number of general reliefs that troops are disposed in depth in a position so that continuous defense of the sector will be assured by means of successive interior reliefs. As an example of interior reliefs, we will consider a division holding a part of the front with two regiments disposed in the first position, one regiment near the second position in billets, and the fourth still farther to the rear in complete rest. These regiments, by a system of interior reliefs, will rotate to equalize the tours of duty in the first position. Similarly the battalions of the regiments in the first position will rotate to give equal divisions of time to each in the first lines. Assuming that a period of six to eight days spent in the front line is a fair average, and considering the fact that troops are disposed in depth throughout the three lines, different combinations of reliefs are possible. The work of making out the schedule of reliefs falls upon a division of the general headquarters.
The sector period is variable with the activityof the enemy and conditions of life in the trenches. During the German offensive at Verdun the sector period was four days, while in Lorraine during that time the same size unit could remain in the trenches for three months without necessity of relief.