ints commanded by the flanking fire of machine
guns. High entanglements (known as abatis) may be made by felling
trees toward the enemy, and similar entanglements made of brushwood
are useful in emergency.

Low Entanglements are formed of pickets two feet high, 2-1/2 inches
in diameter, wired in all directions. Vegetation renders the
entanglement invisible from the enemy and from aerial observation.
This type may also be placed in shallow excavations which are
concealed from the enemy and partly protected from artillery fire.
Sharpened stakes, with their points hardened by fire, driven obliquely
into the ground, may also be used.

Loose Wire in the form of loops of small diameter fastened to
stakes, or wire laid along the ground and attached at the ends, or
spirals of barbed wire in racks, is used for entanglements. It is
reported that this form is coming into considerable use, but the
details have not been published. Such entanglements are much harder to
locate by aerial observation.

* * * * *

The following are a number of criticisms made by Lieut. Henri Poire of
the French army, detailed as instructor at Plattsburg, upon the system
of field works constructed by the 17th and 18th Provisional Training
Regiments. The ground was of loose sand, with some gravel at a depth
of about six feet.

1. Dimensions of trenches as laid out were not followed.
(a) Bottom of trenches behind firing steps too narrow.
(b) Firing step too deep. It should never be more than 3 feet 4
inches below berm of parapet.
(c) Parapet much too thin in most cases. It should be at least
three feet thick.
(d) Communication trenches (boyaux) generally too narrow.
(e) Islands in communication trenches should never be less than
10 x 12 yards--otherwise one shell will demolish the entire
passageway.

2. Revettment work not well anchored. In some cases too many wires
from supports fastened to one dead man. Another fault is that dead
men were not buried deeply enough in the ground, nor far enough back
from the trench. In one case a dead man (a stake) supported all four
sides of an island in a communication trench. The destruction of this
post would have completely blocked every passage around the island.
Furthermore, dead men rot quickly and tend to break off. It is
necessary, therefore, to have a number of them, each holding only a
portion