 Salan also constructed a heavily patrolled system of barriers to limit infiltration from Tunisia and Morocco.The best known of these was the Morice Line (named for the French defense minister, André Morice), which consisted of an electrified fence, barbed wire, and mines over a 320-kilometer stretch of the Tunisian border.The French military command ruthlessly applied the principle of collective responsibility to villages suspected of sheltering, supplying, or in any way cooperating with the guerrillas.