During his tenure as MACV commander, Abrams saw American strength reach its peak of 543,482 troops in April 1969, and also witnessed the departure of the last United States Army combat unit (3rd Battalion, 21st Infantry) from Vietnam in August 1972. Abrams was appointed Chief of Staff of the United States Army in june 1972, a position he held until his death.
Although when the U.S. troop strength fell to around 30,000, it was more than he would have preferred, Abrams maintained a relentless pressure on the Vietcong and North Vietnamese positions in South Vietnam. He gradually shifted American strategy from the search and destroy operations that Westmoreland had favored towards defending the population of South Vietnam. He also presided over a vast enhancement of the South Vietnamese armed forces, leaving them with one of the largest and best equipped armies in the world. To give time for Vietnamization to succeed, Abrams planned and executed U.S.-South Vietnamese raids against the North Vietnamese supply lines in Cambodia in 1970 and in Laos in 1971.