Lemnitzer was promoted to the rank of Major General and in 1945 was one of the senior officers that negotiated the German surrender. He would later be accused of making it possible for some leaders of the Nazi Party to elude investigations for war crimes.
After the Second World War he was assigned to the Strategic Survey Committee of the Joint Chiefs of Staff. In 1950 he was placed in command of the 11th Airborne Division and saw action in the Korean War.
In March 1955 Lemnitzer was promoted to the rank of General and named Commander of U.S. Army Forces in the Far East. He was named Chief of Staff of the Army in July 1957 and he was appointed as Chairman of the Joint Chiefs of Staff in September 1960.
During the Bay of Pigs crisis Lemnitzer advocated that President John F. Kennedy launch an attack on Cuba. Kennedy refused and reminded him "over and over again" that he would not commit U.S. combat forces to save the operation. Kennedy told Arthur Schlesinger that he would not be "overawed by professional military advice". Schlesinger added "he thought Lemnitzer was a dope." Some time after this event Lemnitzer described Kennedy's attitude as "absolutely reprehensible, almost criminal."
On 20th July, 1961, at a National Security Council meeting, Lemnitzer presented Kennedy with an official plan for a surprise nuclear attack on the Soviet Union. Kennedy was disgusted and walked out of the meeting and later remarked to Secretary of State Dean Rusk "and we call ourselves the human race."
In April 1961 General Edwin Walker, commander of the 24th Infantry Division in Europe, was accused of indoctrinating his troops with right-wing literature from the John Birch Society. With the agreement of President John F. Kennedy, Defense Secretary Robert S. McNamara relieved Walker of his command and announced an investigation into the affair. Kennedy was accused of trying to suppress the anti-Communist feelings of the military. Walker resigned from the army in protest about the way he had been treated.
David Talbot argues in his book, Brothers: The Hidden History of the Kennedy Years, that Walker's indoctrination program had been endorsed by General Lemnitzer. Talbot quotes a letter from Lemnitzer to Walker saying that he found his efforts "interesting and useful."
On 13th March, 1962, General Lemnitzer presented Robert McNamara with a top-secret memo, urging President Kennedy to order a variety of shocking incidents to create a rationale for invading Cuba. Code named Operation Northwoods, the memo suggested that the administration should arrange a terror campaign in Miami and Washington that would create international revulsion against the government of Fidel Castro.
President John F. Kennedy summoned Lemnitzer to the Oval Office on 16th March, 1962, where they discussed Operation Northwoods. Kennedy rejected the idea and three months later he told Lemnitzer that he was being moved from the Pentagon to become Commander of U.S. Forces in Europe.
Lemnitzer took up the appointment in November 1962. He became Supreme Allied Commander of NATO in January 1963 and held the post until 1969.
After retiring from the army he was a member of the American Security Council (ASC), the lobby for the military-industrial complex. The ASC was formed by Robert Wood and Robert R. McCormick in 1955. Other members of this organization included Douglas MacArthur, Sam Rayburn, Ray S. Cline, Thomas J. Dodd, W. Averell Harriman, Nelson A. Rockefeller, Eugene V. Rostow, John G. Tower and Patrick J. Frawley.
Lyman Louis Lemnitzer died on the 12th November 12, 1988.