flame
throwers, the Allies soon gained the ascendency.

[Illustration: Four photographs of tanks.]
TYPES OF LAND BATTLESHIPS DEVELOPED BY ALLIES AND GERMANS
British light tank, of 1918, with turret action and high speed
British Tank of earliest type, as used at Cambrai.
German land battleship in 1918 on the Western front
Improved French Tank first used in Champagne in 1916.

[Illustration: Painting]
CHARGING ON GERMAN TRENCHES IN GAS MASKS
Each British soldier carried two gas-proof helmets. At the first alarm
of gas the helmet was instantly adjusted, for to breathe even a whiff
of the yellow cloud meant death or serious injury. This picture shows
the earlier type before the respirator mask was devised to keep up
with Germany's development of gas warfare.

The first use of asphyxiating gas was by the Germans during the first
battle of Ypres. There the deadly compound was mixed in huge reservoirs
back of the German lines. From these extended a system of pipes with
vents pointed toward the British and Canadian lines. Waiting until air
currents were moving steadily westward, the Germans opened the
stop-cocks shortly after midnight and the poisonous fumes swept slowly,
relentlessly forward in a greenish cloud that moved close to the earth.
The result of that fiendish and cowardly act was that thousands of men
died in horrible agony without a chance for their lives.

Besides that first asphyxiating gas, there soon developed others even
more deadly. The base of most of these was chlorine. Then came the
lachrymatory or "tear-compelling" gases, calculated to produce
temporary or permanent blindness. Another German "triumph" was mustard
gas. This is spread in gas shells, as are all the modern gases. The
Germans abandoned the cumbersome gas-distributing system after the
invention of the gas shell. These make a peculiar gobbling sound as they
rush overhead. They explode with a very slight noise and scatter their
contents broadcast. The liquids carried by them are usually of the sort
that decompose rapidly when exposed to the air and give off the acrid
gases dreaded by the soldiers. They are directed against the artillery
as well as against intrenched troops. Every command, no matter how
small, has its warning signal in the shape of a gong or a siren warning
of approaching gas.

Gas masks were speedily discovered to offset the dangers of poison gases
of all kinds. These were worn not only by troop