Less than three weeks after the overthrow of Ngo Dinh Diem, the U.S. Presidency changed hands. On 22 November President Kennedy was assassinated in Dallas and Vice President Lyndon B. Johnson took the reigns of the American government. By late November, when the new president assumed office, the process of political and military disintegration which had begun in South Vietnam following the Diem coup was already well underway. This process continued into the early weeks of 1964 when, in late January, General Nguyen Khanh, the newly appointed commander of I Corps, seized power in a bloodless coup. This second turnover in the government of South Vietnam in less than three months had its most serious impact on the nation’s armed forces. A new series of command changes ensued and again the government’s operations against the Communists suffered. As had been the case in the closing months of 1963, the Viet Cong continued to capitalize on the government’s disarray by expanding its control into previously secure areas. By March the rapidly declining effectiveness of the South Vietnamese military forces led the Johnson Administration to review the earlier decisions to withdraw American servicemen and to cut back the military assistance program. In a 16 March memorandum to President Johnson, Secretary of Defense McNamara warned that “the [military] situation had unquestionably been growing worse” in South Vietnam.[10-1] To counteract this threatening trend, McNamara offered a broad set of recommendations which included a proposal to support a 50,000-man increase in the size of the Vietnamese military and paramilitary forces. The memorandum did not address the question of additional American advisors who might be needed to supervise the proposed expansion. In any case, President Johnson approved McNamara’s plan the following day, thus setting the stage for increases in U.S. military assistance to South Vietnam.[10-2] Shortly after his most recent decision on Vietnam, President Johnson ordered changes in his top civilian and military representatives in Saigon. On 22 June, General William C. Westmoreland, U.S. Army, who had been serving since January as Deputy Commander, USMACV, succeeded General Harkins as ComUSMACV. One day later, on the 23d, President Johnson announced that General Maxwell D. Taylor would replace Henry Cabot Lodge as U.S. Ambassador to the Republic of Vietnam. Taylor, who had been serving since 1962 as the Chairman of the Joint Chiefs of Staff, had been closely associated with the Vietnam problem since his 1961 fact-finding mission. Both he and Westmoreland were thoroughly familiar with U.S. programs and objectives in Vietnam.