Most traditional accounts identify the Linebacker I and Linebacker II campaigns as the most effective and consequential uses of U.S. air power in the Vietnam War. They argue that deep interdiction in North Vietnam played a central role in the defeat of the Easter Offensive and that subsequent strategic attacks on Hanoi forced the North Vietnamese to accept the Paris accords. These conclusions are false. The Linebacker campaigns were rather ineffective in either stopping the Communist offensive or compelling concessions. The most effective and consequential use of U.S. air power came in the form of close air support and battlefield air interdiction directly attacking the North Vietnamese Army in South Vietnam. The success of these air strikes hinged on the presence of a U.S.-operated tactical air control system that incorporated small numbers of ground advisers, air liaison officers, and forward air controllers. This system, combined with abundant U.S. aircraft and a reasonably effective allied army, was the key to breaking the Easter Offensive and compelling Hanoi to agree to the Paris accords. The effectiveness of close air support and battlefield air interdiction and the failure of deep interdiction and strategic attack in the Vietnam War have important implications for the use of air power and advisers in contemporary conflicts in Iraq, Syria, and Afghanistan.