In November 1969, Tully traveled to South Vietnam, currently Vietnam, for the United Service Organization. His "handshake tour" took him to hospitals, radio interviews, and FLIGHT behind enemy lines, courtesy of the 173rd Airborne Brigade, to visit strategic military outposts such as the "Hawks Nest" in the Phum Valley. While in Vietnam entertaining troops, Tully contracted a filarial worm, similar to the creature that causes elephantiasis. After returning to the United States, his condition worsened. Because a blood clot in a major vein shut off circulation, his left leg was amputated close to the hip. The amputation was performed in Laguna Beach, California, close to his home in San Juan Capistrano. Not to be held down, Tully continued his acting in television dramas such as Mission: Impossible and The Rookies. His last feature film role was as a crooked gun dealer in Don Siegel's thriller Charley Varrick (1973), with Walter Matthau.