detachments must be bomb-proof and
fitted with some arrangements for comfort and sanitation. Formerly it
was the custom to provide living accommodation for the full garrison in
casemates inside each fort, but it is now considered better to provide
barrack accommodation in the vicinity and to occupy forts in peace only
by a few caretakers. The shelters in the fort itself can thus be kept at
the minimum required when actually manning the guns. The protection of
the guns and magazines against bombardment is provided, in the British
service, mainly by an earthen parapet over a substantial roof or wall of
concrete, but immediately round the gun an "apron" of concrete is
necessary to withstand the shock of discharge or "blast."

It has been already mentioned that in the old designs a large number of
guns was put in each fort, but with dispersion and improved gun power
this number was much reduced. At first the type of fort adopted was for
four guns, of which the two in the centre were heavy and the two on the
flank of medium power. Such a design was good from the point of view of
the engineer; it gave an economical grouping of magazines and shelters
and was easily adapted to varying sites, and the smaller guns helped the
larger by covering their flanks both towards the sea and also over the
land approaches. But from the point of view of the artillery officer the
arrangement was faulty, for when the guns are too much separated,
ranging has to be carried out separately for each gun. On the other
hand, two guns of the same calibre placed near one another can be fought
simultaneously and form what is known as a "group." In the typical 4-gun
battery described above, the flank guns had to be fought independently,
which was wasteful of officers and staff. Further, in a battery of more
than two guns the arc of fire of the centre guns is much restricted by
that of the guns on either flank.

For these reasons it is now generally recognized that new works should
be designed for only two guns of the same calibre, though 3- or 4-gun
batteries are occasionally used in special circumstances.

Protection of the gun detachments against infantry attack is best
provided by a line of infantry posts outside and on the flanks of the
gun batteries, but as small parties may evade the outposts, or the
latter may be driven in, it is necessary to place round each fort a line
of obstacles sufficient to protect the guns against a rush and to cover
the