4. VENTILATION:

_Natural Ventilation_.--Unless a shelter has been thoroughly ventilated by artificial means, as described below, it must not be slept in or occupied without wearing respirators, until at least 12 hours after a gas attack. It must not be entered at all without respirators on for at least 3 hours. The above refers to cloud gas attacks. In the case of gas sh.e.l.l bombardments the times cannot be definitely stated, as they depend on the nature of the gas used and the severity of the bombardment. With lachrymatory gases the times after which shelters can be used without discomfort may be considerably longer than those mentioned above.

_Ventilation by Fire_.--All kinds of shelters can be efficiently and rapidly cleared of gas by the use of fires. Shelters with two openings are the easiest to ventilate and where possible, dugouts with only one entrance should have a second opening made, even a very small one, to a.s.sist in ventilation.

In dugouts provided with a single exit at the end of a short pa.s.sage, the best results are obtained if the fire is placed in the center of the floor of the dugout and at a height of about 9 inches.

In dugouts provided with a single exit at the end of a long and nearly horizontal pa.s.sage, the best results are obtained if the fire is placed about one-third of the distance from the inner end of the pa.s.sage.

In dugouts provided with two or more exits, the fire should be placed at the inner end of one of the exit pa.s.sages.

In general, 1 pound of dry wood per 200 cubic feet of air s.p.a.ce is sufficient for clearance of any gas. The best fuel is split wood, but any fuel which does not smoulder or give off thick smoke can be used.

The materials for the fire, _e.g._, the split wood, newspaper, and a small bottle of paraffine for lighting purposes, should be kept in a sand bag, enclosed in a biscuit tin provided with a lid. An improvised brazier should be kept ready for use.

The fire must be kept burning for at least ten minutes and the atmosphere in the shelter should be tested from time to time.

_Ventilation by Fanning_.--Dugouts can be ventilated by producing air currents in them by means of special anti-gas fans.

If no anti-gas fans are available, ventilation can be a.s.sisted by flapping with improvised fans such as sand bags, ground sheets, etc.

5. CLEANING OF ARMS AND AMMUNITION:

Rifles and machine guns must be cleaned after a gas attack and then re-oiled. Oil cleaning will prevent corrosion for 12 hours or more, but the first available opportunity must be taken to dismantle machine guns and clean all parts in boiling water containing a little soda. If this is not done, corrosion continues slowly even after oil cleaning and may ultimately put the gun out of action.

After a gas attack, S.A.A. should be carefully examined. All rounds affected by gas must be replaced by new cartridges immediately and the old ones cleaned and expended as soon as possible.

All hand and rifle grenades exposed to the gas should have their safety-pins and working parts cleaned and re-oiled.

All bright parts of light trench mortars, together with all accessories and spare parts exposed to the gas, must be cleaned and wiped dry as soon as possible after the attack and in any case within 24 hours, after which they should be thoroughly coated afresh with oil. The same applies to ammunition which may have been exposed to the gas.

Ammunition which, for any reason, had not been oiled, must be cleaned and oiled and expended as soon as possible.

For details regarding the cleaning of guns and artillery ammunition and signal equipment, see paragraphs 116 and 123.

6. TREATMENT OF Sh.e.l.l HOLES:

In the neighborhood of shelters or battery positions where gas from sh.e.l.l holes is causing annoyance, the holes and the ground round them should be covered with at least a foot of fresh earth. Sh.e.l.l holes so treated should not be disturbed, as the chemical is not thereby destroyed and only disappears slowly.

Concealment From Aerial Observers.

A. 1. An aeroplane cannot conduct reconnaissance at a height of less than 5,000 feet without being within easy range of anti-aircraft artillery; nor of less than 2,000 feet without coming into range of machine-gun and rifle fire.

2. To be observed from such heights, objects on the ground must be distinguished by: (a) Motion.

(b) Color contrast.

(c) Line contrast, or (d) Shadows.

B. Concealment: 1. (a) On warning of hostile aircraft, troops on the march should withdraw to the side of the road (if possible, into shade), or lie down flat in the road and remain motionless.

(b) If it is necessary to continue the march, this should be done in broken detachments, which are far less distinct than continuous column.

(c) Troops in a trench should crouch down in the shadowy side and remain motionless.

(d) Faces should never be turned up, as the high lights on cheek-bones and foreheads then show up distinctly.

(e) Bright metal on arms, equipment and headgear must be kept covered.

2. Artillery wagon-trains, etc., should if possible be halted promptly on warning. When halted, their neutral coloring protects them.

3. Trenches are best concealed: (a) By avoiding, in construction, a too regular outline, and following as far as possible the contours of the ground.

(b) By coloring the parapet and parados to match the ground.

This may be done most quickly by painted canvas; if the latter is not available, by planting or strewing the loose earth with surrounding herbage. In this work care must be taken not to make the covering itself too conspicuous by brightness or monotony of coloring.

(c) By covering the trench itself, where convenient, with a thin material, colored like the parapet and parados.

(d) By avoiding all overt movement of troops in the trenches under observation.

4. Buildings, _e.g._, ammunition dumps, hangars, etc., can be completely concealed by being painted the color of the ground they stand on and fitted with canvas curtains, similarly painted and stretched from the eaves to the ground at a horizontal angle of 35 degrees. These curtains completely eliminate shadows.

5. Success in each work of concealment by camouflage is best a.s.sured by the a.s.sistance of an aeroplane observer to test and correct it.

Orders Governing Intrenchment Problems at Second Plattsburg Training Camp.

HEADQUARTERS PLATTSBURG TRAINING CAMP, PLATTSBURG BARRACKS, NEW YORK.

SEPTEMBER 22, 1917.

DIVISIONAL ENTRENCHING PROBLEM.

General Situation:

The Salmon river forms the boundary line between two states, the "Blue" on the north and the "Red" on the south. War has been declared and the Red Army is mobilizing near Keeseville. Mobilization by the first Blue Army at Plattsburg has been completed.

Special Situation, Blue:

Our advanced troops are holding the line of the Salmon river against strong detachments of the Red Army. The commanding general of the Blue Army has decided to establish a second position on the line, _Bluff Point to the bend_ (248) _in the Saranac river_.

The following order is issued by the Division Commander:

HEADQUARTERS, 101st Div., PLATTSBURG, N.Y.

23 Sept., '17, 9:00 A.M.

FIELD ORDERS, No. 1.

1. Our advanced troops are holding the line of the Salmon river.

2. This division and 1 Brigade 102 Division will entrench along the line: _Bluff Point_--_Chateaugay Branch Railroad_--_Saranac River_ (248).

3. (a) The Chief of Artillery will prepare the positions, and lines of communication for his Brigade, determine his sectors, and submit his plan of action.

(b) The 1st Brig. and 2 Bns. 267th Inf. will entrench the sector, _Saranac River_ (248) to _Sand Road_, exclusive. The 2nd Brig. will entrench the sector _Sand Road to Bluff Point_, both inclusive. The supports will entrench on the line, _Saranac River_ (182)--_Cliff Haven_.

(c) The Reserve--1 Brig. 102 Div. less 2 Bns., will construct crossings on the _Saranac River_--under direction of the Chief of Engineers, and prepare them for defense.

(d) The Chief of Engineers will supply tools for entrenching and lay out the lines of entrenchments. He will repair the following trunk roads: _Peru Road_, _Sand Road_, _Lake-Sh.o.r.e Road_; and construct a transverse trunk line road from _Pulp Mill to O'Connell's Farm_, and the necessary tram lines. The Engineer Depot for stores and material will be established at _Plattsburg Barracks_.

(e) The Chief Signal Officer will establish necessary lines of communication, utilizing equipment at _Plattsburg Barracks, Central Station_. Aero Squadron at _Chazy_.