e prevented the use of the field gun.

MEDIUM GUNS.--Medium guns, firing a 60-pound shell, are principally
employed in counter-battery work and in fulfilling the functions of
18-pound field guns at a greater range and with greater force. _Medium
Howitzers_ occupy the same relative position, their offensive power
being greater than that of the Field Howitzer.

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HEAVY GUNS.--Heavy guns of 6-inch calibre, firing a shell of 100
pounds, are used against targets beyond the range of light and medium
guns, and with greater effect. _Heavy Howitzers_, of 8-inch or
9.2-inch calibre, are principally employed against covered batteries
and strong defences, or for destroying wire entanglements with
instantaneous fuses.

SUPER-HEAVY GUNS.--Super-heavy guns of a calibre of 9.2 inches and
upwards are usually carried on railway mountings, and while they
possess a high muzzle velocity, considerable shell-power, and a high
degree of mobility (which enables them to come into action in any part
of the battlefield where suitable rails have been laid), their arc of
fire is very restricted and their "life" is short. _Super-Heavy
Howitzers_, of 12-inch or 18-inch calibre, possess similar advantages
and disadvantages to super-heavy guns. Their normal use is the
destruction of permanent defences, the breaking down of bridges, etc.
The 12-inch weapon is also used on tractor-drawn mountings and is
highly effective in counter-battery work.

The table on p. 173 is based upon particulars given on p. 26 of "Field
Service Regulations," vol. ii. (1921).

ROYAL ENGINEERS

"All arms are responsible for the construction of their own works of
defence. It is the duty of the Royal Engineers to assist them by
engineer reconnaissances, plans, advice, technical supervision,
provision of materials and the construction of works requiring special
technical skill. . . . Although trained as fighting troops, engineers
should be regarded as reserves to be used only as a last resource;
casualties in their ranks are not easy to replace, and they may become
needlessly involved in the fighting and lost for work which may have an
important bearing on the operations" ("Field Service Regulations," vol.
ii. (1921)).

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TABLE OF ARTILLERY RANGES

Weapon Effective Range (Yds.)

_Light Artillery_ H.E. Shell Shrapnel
Pack Guns (2.75 in.) 5,800 4,000
Pack Howi