rate will be from 2 to
2-1/2 miles per hour.

634. The marching capacity of trained infantry in small commands is
from 20 to 25 miles per day. This distance will decrease as the size
of the command increases. For a complete division the distance can
seldom exceed 12-1/2 miles per day unless the division camps in
column.

635. In large commands the marching capacity of troops is greatly
reduced by faulty march orders and poor march discipline.

The march order should contain such instructions as will enable the
troops to take their proper places in column promptly. Delay or
confusion in doing so should be investigated. On the other hand,
organization commanders should be required to time their movements so
that the troops will not be formed sooner than necessary.

The halts and starts of the units of a column should be regulated by
the watch and be simultaneous.

Closing up during a halt, or changing gait to gain or lose distance
should be prohibited.

(_C.I.D.R., Nos. 2 and 12._)

_PROTECTION OF THE MARCH._

_General Considerations._

636. A column on the march in the vicinity of the enemy is covered by
detachments called "advance guards," "rear guards," or "flank guards."
The object of these covering detachments is to facilitate the advance
of the main body and to protect it from surprise or observation.

They facilitate the advance of the main body by promptly driving off
small bodies of the enemy who seek to harass or delay it; by removing
obstacles from the line of advance, by repairing roads, bridges, etc.,
thus enabling the main body to advance uninterruptedly in convenient
marching formations.

They protect the main body by preventing the enemy from firing into it
when in close formation; by holding the enemy and enabling the main
body to deploy before coming under effective fire; by preventing its
size and conditions from being observed by the enemy; and, in
retreat, by gaining time for it to make its escape or to reorganize
its forces.

637. Tactical units should not be broken in making details for
covering detachments.

638. The march order of the whole command should explain the
situation, and, among other things, detail the commander and troops
for each covering detachment. It should specify the route to be taken
and the distance to be maintained between the main body and its
covering detachments. It should order such reconnaissance as the
commander specially desires to have made.

The