The Bundys were close to Henry L. Stimson. As Secretary of State under Herbert Hoover, in 1931 Stimson appointed Harvey Bundy as his Assistant Secretary of State. Later Bundy served again under Stimson as Secretary of War, acting as Special Assistant on Atomic Matters, and serving as liaison between Stimson and the director of the Office of Scientific Research and Development, Vannevar Bush. William and McGeorge grew up knowing Stimson as a family friend and colleague of their father. The senior Bundy also helped implement the Marshall Plan.