Not since World War II had bombers been employed in an operation of this scope. All previous air campaigns, including the initial Linebacker carried out in May-October 1972, were "limited," designed to interdict the overland routes by which the North resupplied its regular units and Viet Cong forces operating in South Vietnam. Linebacker II was to be different. The intent was to destroy all major target complexes in the Hanoi and Haiphong areas, using an all-weather force of heavy B-52s and smaller F-111 attack aircraft by night while tactical aircraft would continue to press daytime attacks. The campaign unfolded over the 12-day period of December 18-29, 1972. After 11 days of bombing, Hanoi was ready for peace negotiations.