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* An anti-tank defense favored by the U. S. Army is "concertina rolls"—heavy wire coiled like a spring which is stretched across roads to foul the wheels and tracks of advancing trucks or tanks. Says the Infantry Journal: "In a recent test a 1 ½-ton truck hit a series of concertina rolls at 22 m.p.h. It took two mechanics four hours to free it enough to be towed. The wire . . . is so heavy that it cannot be cut by ordinary wire cutters. It takes bolt cutters to do it."