This is the sixth volume in the history of the Office of the Secretary of Defense. It covers the last four years of the Lyndon Johnson administration--March 1965-January 1969, which were dominated by the Vietnam conflict. The escalating war tested Robert McNamara''s reforms and abilities and shaped every aspect of Defense Department planning, programming, and budgeting. The demands posed by Vietnam weakened U.S. conventional forces for Europe, forced political compromises on budget formulation and weapons development, fueled an inflationary spiral, and ultimately led to McNamara''s resignation. The credibility gap grew, dissipating public confidence in government and left the Johnson administration to confront massive civil disobedience and domestic rioting--much of it directed against the Pentagon. Vietnam also eclipsed major crises in the Dominican Republic, the Middle East, Korea, and Czechoslovakia. McNamara''s successor, Clark Clifford, operating under President Johnson''s new guidelines, spent much of his 11-month tenure as secretary attempting to disengage the United States from the Vietnam fighting.Vietnam held center stage and frustrated McNamara''s plans to reduce Defense budgets or downsize the military services and soured the secretary''s workings with Congress. It cast a long shadow over U.S.-Soviet relations, alienated to a greater or lesser degree the NATO allies, and eroded congressional support for defense programs as well as military assistance. For the foreseeable future, it remains an emotionally charged issue that challenges Americans'' views of themselves. Yet throughout these four years OSD still had to deal with a wide range of policy matters, international instability, and other contingencies. Beginning in the spring of 1965 with the intervention in the Dominican Republic and ending in late 1968 with the release of U.S. Navy crewmen held captive by the North Koreans, McNamara and Clifford handled a series of international crises and threats, defusing some, making the best of others. The final four years also witnessed extensive and repeated contacts between Washington and Moscow on matters of mutual interest such as nuclear proliferation, arms control, and a Middle East settlement. Dramatic changes in the composition and strategy of NATO''s military alliance tested the durability of U.S. and European commitment. War between superpower surrogates in the Middle East threatened to expand from a regional conflict to a global one. The role that McNamara and Clifford played in often neglected subtexts of the period provides readers with a wider perspective in which to place Vietnam and to appreciate the ramifications of the war on national security policy.Movers and Shakers * DoD''s Senior Leadership * Civilian-Military Divide * Commander in Chief * National Security Policymaking Apparatus * Mastering Pentagon * II. Vietnam: Escalation Without Mobilization * Pondering Escalation * Hidden Escalation * More Troops, More Money * Enemy Dictates Course of Action * McNamara''s 180-Degree Turn * Conflicting Assessments * President''s Decision * III. Air War Against North Vietnam, 1965-1966 * Targeting North Vietnam * Rolling Thunder * Working Toward an Extended Bombing Pause * Resuming Rolling Thunder * POL Debate * Rolling Thunder: Indecision, Discord, and Escalation * IV. Paying for a War: Budgets, Supplements, and Estimates, 1965-1967 * FY 1966 Defense Budget * 1965 Supplemental * August Supplemental Amendment to 1966 Budget * FY 1966 Supplemental * FY 1967 Defense Budget * Vietnam Spending and Economy * V. Vietnam: Escalating a Ground War, July 1965-July 1967 * Planning a Ground War * Hard Choices * Cost-Effective Deployments * Barrier Concept * More Troops, More Questions * Search for a Winning Formula * VI. More Than Expected: * Supplementals and Budgets, 1966-1968 * Enacting FY1966 Supplemental * FY 1967 Defense Budget * Need for a FY 1967 Supplemental Budget * Price of Escalation * Enacting FY1967 Supplemental