o between the troops, the rearward magazines, and the railhead.
Since traction waggons are restricted to made roads, the direct
communication with the troops must be kept up by columns of draught
animals, which can move independently of the roads. The waggons of
provisions, therefore, which follow the troops, and are filled daily,
must come up with them the same day, or there will be a shortage of
food. This is only possible if the troop column does not exceed a
certain length and starts at early morning, so that the transport
waggons, which, at the end of the march, must be driven from the rear to
the head of the column, can reach this before the beginning of the
night's rest. The fitness of an army for attack can only be maintained
if these supplies are uninterrupted; there must also be a sufficient
quantity of tinned rations and provisions which the soldiers can carry
with them. If the length of the columns exceeds the limit here laid
down, the marches must be proportionately shortened. If unusually
lengthy marches are made, so that the provision carts cannot reach the
troops, days of rest must be interposed, to regulate the supply. Thus
the capacity of an army to march and to carry out operations is directly
dependent on the possibility of being fed from the rear. A careful
calculation, based on practical experiences, shows that, in order to
average 20 to 22 kilometres a day--the minimum distance required from an
army--no column on a road ought to exceed a length of about 25
kilometres This consideration determines the depth of the army corps on
the march, since in an important campaign and when massing for battle
troops seldom march in smaller bodies than a corps.

This calculation, by which the conditions of modern war are compulsorily
affected, makes it highly necessary that the system of supplies and
rations should be carefully organized. The restoration of any destroyed
railways, the construction of light railways, the organization of
columns of motor transport waggons and draught animals, must be prepared
by every conceivable means in time of peace, in order that in war-time
the railroads may follow as closely as possible on the track of the
troops, and that the columns may maintain without interruption
continuous communications between the troops and the railhead. In order
to keep this machinery permanently in working order, and to surmount any
crisis in bringing up supplies, it is highly advisable to have an