y
commander, on the line of the old Amiens defences between Mezieres,
Marcelcave, and Hamel. Subsequently, as General Grant could ill be
spared from his proper duties, he was directed to hand over command of
his force to Major-Gen. G. G. S. Carey. Except for General Carey's
force there were no reinforcements of any kind behind the divisions,
which had been fighting for the most part since the opening of the
battle. . . . On March 28 our line from Marcelcave to the Somme was
manned by Carey's Force, with the 1st Cavalry Division in close
support. . . . On March 29 the greater part of the British front south
of the Somme was held by Carey's Force, assisted by the 1st Cavalry
Division and such troops of the divisions originally engaged as it had
not yet been found possible to withdraw. In rear of these troops, a
few of the divisions of the V. Army were given a brief opportunity to
reassemble" (Sir D. Haig's Dispatches).

TANKS

Tanks are moving fortresses containing light artillery, machine guns,
and rifles, and while capable of inflicting heavy losses by fire they
can also destroy obstacles, weapons, and personnel. Their garrisons
are protected against the fire of small arms and from shrapnel bullets,
but they are very vulnerable to other forms of artillery fire. Their
mobility and radius of action are governed by the amount of petrol
carried and by the physical endurance of the crew, but except over deep
cuttings, {175} broad streams, swamps, very heavily shelled ground,
rocky and mountainous country, or in thick woods they can move without
difficulty. "The power of delivering successful surprise attacks
against almost any type of defences is one of the most important
advantages of the use of Tanks in large numbers" ("Field Service
Regulations," vol. ii. (1921)).

During the _First Battle of the Somme_ (September 1-November 18, 1916)
"Our new heavily armoured cars, known as 'Tanks,' now brought into
action for the first time, successfully co-operated with the infantry,
and coming as a surprise to the enemy rank and file, gave valuable help
in breaking down their resistance. . . . These cars proved of great
value on various occasions, and the personnel in charge of them
performed many deeds of remarkable valour" (Sir D. Haig's Dispatches).

AIRCRAFT

Two classes of Aircraft are used in the field. Aeroplanes, which are
self-propelled and have an almost unlimited radius of action; and Kite
Balloons, whi