General Raoul Salan commanding the French Army in Algeria

Late in 1957, General Raoul Salan, commanding the French Army in Algeria, instituted a system of quadrillage (surveillance using a grid pattern), dividing the country into sectors, each permanently garrisoned by troops responsible for suppressing rebel operations in their assigned territory. Salan's methods sharply reduced the instances of FLN terrorism but tied down a large number of troops in static defense. Salan also constructed a heavily patrolled system of barriers to limit infiltration from Tunisia and Morocco.