In order for obstacles to be effective, they must be covered by small-arms
fire, and if extensive, also by artillery fire. In North Africa the Italian Trieste
Division employed a system of observation and signalling posts to prevent the
British from clearing gaps in the minefields. These posts, armed with light
machine guns, are manned from dusk to dawn, with at least two men on duty at
all times. They are located both inside the minefield and along the far edge.
Prisoners of war stated that, "mines were always laid about 1 yard apart,
except when the supply was inadequate in which case they were laid either
haphazardly or from 2 to 4 yards apart." It is thought that reference is here made
to a density of one mine per yard of front, since if the mines were spaced as
close as one yard apart the explosion of a single mine would probably touch off
the entire minefield by sympathetic detonation.
Much difficulty appears to have been experienced by the enemy in the marking
of minefields. Various methods have been reported. One method, which is
believed not to have been heretofore reported, is to use a system of wooden
stakes: high stakes to mark the near edge, short stakes to mark the far edge and