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. Through dialogue with Senator Arthur Vandenberg, he helped draft the Vandenberg resolution, which led to the establishment of NATO. Marshall was in poor health and had never been a workaholic. He turned over major responsibilities to his deputies. especially Lovett, and refused to be troubled by minutiae. By 1948, with frailties building up, Marshall's participation was further curtailed. He said, "The fact of the matter is that Lovett bears the principal burden as I get away whenever possible."