Lovett was a core member of the group of foreign policy elders known as "The Wise Men", and was deemed an "architect of the cold war" by social scientist G. William Domhoff, in his 1970 book, The Higher Circles: The Governing Class in America.

Lovett served with distinction, overseeing the massive expansion of the Army Air Forces and the procurement of huge numbers of aircraft during World War II.

[13] In December 1945, Lovett returned to Brown Brothers Harriman, only to be called back to Washington a little more than a year later to serve with General George Marshall as undersecretary of state.

Like Marshall, Lovett believed that the United States erred seriously at the end of World War II by disintegrating the military.

Lovett's efforts to meet rearmament and preparedness goals suffered in 1952 from a major dispute between the federal government and the steel industry.

Lovett supported the president's action as essential to maintaining defense production and expressed serious concern about the strike's effects on the nation's military capabilities.

"[17] By the end of the Truman administration, the Defense Department had met successfully the challenges of the Korean War mobilization and embarked on a long-term preparedness effort.

Besides the preparedness issue, Lovett inherited a number of other matters that were still unresolved in the early 1950s, including the proper military role of nuclear weapons.

Although he recognized that real unification could result only from an evolutionary process, not from legislative edict, as the end of his term approached, he discerned the need for changes in the National Security Act beyond those made in 1949.

Commenting about unification at a press conference a week before he left office, Lovett observed that the Department of Defense would have to be reorganized substantially if the United States became involved in a major conflict.

He put forward his recommendations in a long letter to President Truman on November 18, 1952, proposing clarification of the secretary of defense's relationship to the president, the Joint Chiefs of Staff, and the military departments; redefinition of JCS functions; reorganization of the military departments; and reorganization and redefinition of the functions of the Munitions Board and the Research and Development Board.

Lovett meant his recommendations for practical consideration by his successor, and they indeed played an important role in the formulation of a reorganization plan during the early months of the Eisenhower administration.

Concerned about the need for an orderly post-election changeover in the Department of Defense, Lovett met several times during the transition period with the incoming secretary, Charles E. Wilson, and made sure that he was thoroughly briefed on current issues.

After Lovett left office on January 20, 1953, he returned again to Brown Brothers Harriman, where he remained active as a general partner for many years.

His work in completing the Korean War mobilization and in planning and implementing the long-range rearmament program, as well as his proposals to restructure the Department of Defense, were among his major contributions.