Among the early secretaries of defense, James Forrestal adopted the generalist perspective while Robert McNamara was a functionalist. McNamara's tenure was significant for his efforts to expand the range of issues that the secretary of defense had control over and the methodology used in making decisions. Until McNamara, even functionalist-oriented secretaries of defense largely restricted themselves to managing the budgetary process and mediating between inter service rivalries. McNamara sought and acquired a voice in designing defense policy. In doing so he brought Planning, Programming, and Budgetary Systems (PPBS) analysis to the Defense Department. As was commonplace in other government bureaucracies, the Defense Department 's budget was organized by department (Army, Navy, Air Force) and broken down into such traditional categories as personnel, maintenance, and construction. Under PPBS "all military forces and systems were grouped into output-oriented programs according to their principal mission [conventional defense of Europe, nuclear deterrence], even though mission cut across traditional service boundaries categories." Cost-benefit calculations were then made on whether or not to acquire a new system. Based on this type of decision calculus, the B-70 manned bomber, the Skybolt missile, and nuclear navel vessels were rejected while the Poseidon submarine, F-111 fighter, and the Minuteman 3 missile were accepted.