High quality reprint of a recently declassified 1971 study. This CHECO report on Lam Son 719, the South Vietnamese incursion into Laos in February and March 1971, is an interim narrative of what was one of the most significant military actions in Southeast Asia since the enemy's 1968 Tet Offensive. It also is a report on one of the most fundamental problems faced by Americans in the Vietnam conflict--the proper employment of American technological superiority, mainly air power, against an enemy highly skilled in the elusive art of jungle warfare and equipped with modern sophisticated weaponry with the exception of aircraft. Lam Son 719 was the first major operation of its kind - a cross-border activity in which large South Vietnamese ground forces operated independently without U.S. Army ground advisors but with almost complete dependence upon U.S. air support. Yet in Lam Son 719, some of the problems associated with the U.S. effort since 1962 reappeared and had to be resolved to meet the particular situation. Primary among these was the before-the-fact coordination of air support for ground or airmobile operations to fit the needs of a fluid ground situation. Also of significance was the problem of locating the enemy and bringing the maximum firepower to bear on him. Despite these problems, Lam Son 719 showed that a large Vietnamese ground force, which had remained on the sidelines for years, could move into the enemy stronghold given U.S. air support. This was a critical test of its capability, a test which would have a great impact upon plans for American withdrawal from Vietnam.