In 1969 Haig became an assistant to National Security Adviser Henry Kissinger. He became vice chief of staff of the Army, the second-highest-ranking position in the Army, in 1972. After the 1973 resignation of H. R. Haldeman, Haig became President Nixon's chief of staff. Serving in the wake of the Watergate scandal, he became especially influential in the final months of Nixon's tenure, and played a role in persuading Nixon to resign in August 1974. Haig continued to serve as chief of staff for the first month of President Ford's tenure. From 1974 to 1979, Haig served as Supreme Allied Commander Europe, commanding all NATO forces in Europe. He retired from the Army in 1979 and pursued a career in business.