Eroded by the political side-effects of the battlefield developments, South Vietnam’s fragile power structure became increasingly unstable. The last five months of 1964 brought frequent changes in the Saigon government although General Khanh was able to maintain a semblance of control until December. The turmoil then climaxed when Air Vice Marshal Nguyen Cao Ky, the commander of the Vietnamese Air Force, engineered a bloodless coup that forced Khanh from the Saigon political scene. The frequent changes of government coupled with the stepped-up Viet Cong military pressure throughout Vietnam produced a downward spiral in the effectiveness of the republic’s armed forces. By the end of the year it was becoming increasingly doubtful that the government could stave off total collapse even with the increased volume of military assistance it was already receiving from the United States. Against this backdrop of Communist military activities, unprecedented political instability on the part of the South Vietnamese, and mounting combat losses, American military involvement in Vietnam deepened. _A Restructured Military Assistance Command_ In many respects 1964 was a year of transition for the U.S. Military Assistance Command, Vietnam. Not only did the command experience a change in leadership when General Westmoreland replaced General Harkins as ComUSMACV, but it was thoroughly reorganized in preparation for the more vigorous U.S. advisory program which was expected to begin about midyear. The major organizational change within MACV took place on 15 May when the MAAG was abolished and its staff integrated into that of the senior command. In June MACV itself was restructured under a new table of distribution. These changes reflected the anticipated influx of advisors and support personnel, and therefore concerned the Army more than the other U.S. armed services. Initially, the number of Marine billets on the restructured Military Assistance Command staff did not change substantially. Twenty-four Marines (15 officers and nine enlisted) were included in the new table of distribution. This represented a net increase of only one over the number previously assigned to the MAAG and MACV staffs. By the end of September, however, Marines temporarily assigned to the MACV staff from FMFPac commands brought the on-board strength to 37. Another increase occurred in the early fall when eight more permanent Marine billets (three officers and five enlisted) were approved. _Changes in Marine Leadership_