respirators to be put on immediately, the gas is
apparent.

H. Action During a Gas Attack:

(1) PROTECTIVE MEASURES:

There should be as little moving about and talking as possible in the
trenches. Men must be made to realize that with the gas now used by
the enemy, observance of this may be essential for their safety.

When an attack is in progress, all bodies of troops or transport on
the move should halt and all working parties cease work until the gas
cloud has passed.

If a relief is going on, units should stand fast as far as possible
until the gas cloud has passed.

Supports and parties bringing up bombs should only be moved up if the
tactical situation demands it.

If troops in support or reserve lines of trenches remain in, or go
into, dug-outs, they must continue to wear their anti-gas appliances.

Officers and N.C.O's must on no account remove or open up the masks of
the box respirators or raise their helmets to give orders. The
breathing tube may be removed from the mouth when it is necessary to
speak, but it must be replaced.

Men must always be on the look-out to help each other in case an
anti-gas device is damaged by fire or accident. When a man is wounded,
he must be watched to see that he does not remove his respirator or
helmet until he is safely inside a protected shelter; if necessary,
his hands should be tied.

Men must be warned that if they are slightly gassed before adjusting
their respirators or helmets they must not remove them. The effect
will wear off.

(2) TACTICAL MEASURES:

From the point of view of protection against gas, nothing is gained by
men remaining in unprotected dug-outs or by moving to a flank or to
the rear. It is, therefore, desirable that on tactical and
disciplinary grounds all men in the front line of trenches should be
forbidden to do these things. In support or reserve lines where there
are protected dug-outs, it is advisable for men to stay in them unless
the tactical situation makes it desirable for them to come out.

Nothing is gained by opening rapid rifle fire unless the enemy's
infantry attacks. A slow rate of fire from rifles and occasional short
bursts of fire from machine guns will lessen the chance of their
jamming from the action of the gas and tends to occupy and steady the
infantry.

It should be remembered that the enemy's infantry cannot attack while
the gas discharge is in progress and is unlikely to do so for an
appreciab