A recent report gives a brief summary of some engineer lessons that
were learned during the advance of the British Eighth Army from Benghazi to
Tripoli. The operations during the advance demonstrated very clearly the
effectiveness of skillfully placed mines and booby traps in delaying an
advancing enemy, even though in most cases the obstacles were not covered by fire.
The enemy delaying tactics included demolition of bridges and culverts
and the systematic cratering of causeways and roads, wherever defiles occurred
through sand dunes, steep rock, or sabakha.* The delaying effect of demolitions
was greatly increased by mines and booby traps. The clearing of the latter
imposed a heavy task and a very great strain on the engineer units, which were
already heavily committed in overcoming the demolitions.
All physical obstacles were liable to be associated either with heavy
charges or antipersonnel mines. Barbed wire on stakes was in one case dragged
across the road, and to each stake there was attached a pull-igniter in a prepared
charge. A barrel obstacle over a culvert was heavily charged and wired, so
that removal of the barrels destroyed the culvert and produced another obstacle. The
sowing of craters with "S" mines (antipersonnel), and the concurrent mining
with antitank mines of diversion on either side, was a profitable enterprise of
the enemy sappers. It resulted in very considerably extending the time taken to
clear a passage. The "S" mines were placed in the spoil on the lip of the
crater. Tellermines were carefully placed in a radius of 50 yards on
either side of the road on the line of likely diversions, and in many
cases this minefield was again protected by "S" mines.
Enemy minelaying showed every evidence of free improvisation, and little
evidence of well-rehearsed drills or consistent policy. Spacings,
patterns, wiring-in, and booby-trapping all varied widely, and many
minefields were laid at less than the minimum safe spacing to avoid
blast or sympathetic detonations.
Concealment of buried mines proved a major factor in determining the
delay imposed. Many hundreds of mines were detected by eye and lifted without
resort to detectors, recently disturbed earth providing the necessary clues.
Enemy demolition work in ports, while elaborate and fairly effective, was misdirected.
The destruction of side-cut roads on steep hillsides was not fully effective
when large charges were placed by shafts sunk on the uphill side of the road. It
has been shown that the addition of a smaller charge on the downhill side destroys
any "shoulder" on which a repair road could be built. The Germans omitted to
do this in one instance, and no retaining walls were required for immediate
Enemy failure to destroy certain water reservoirs was of great assistance
to the advance. In view of the excellent results obtained from boring
rigs, mere demolition of sources cannot impose much delay.
*A smooth, flat, often saline, plain, sometimes covered after a rain by a shallow lake.