Politics in South Vietnam (aka the Republic of Vietnam) have long been overlooked in most English-language accounts of the Vietnam War, especially during the final years of the conflict. But the breakdown of the Saigon government’s legitimacy in the eyes of its own anti-Communist constituents during this period was decisive in determining the outcome of the war. This chapter explores the wave of anti-Communist solidarity that swept through South Vietnam’s cities and provincial towns following the 1968 Communist Tet Offensive. It analyzes the South Vietnamese state’s ambitious efforts to implement economic, agricultural, and political reforms. And it demonstrates that President Nguyễn Văn Thiệu’s bid to monopolize political power, following clashes with South Vietnam’s civilian parties and institutions, dealt a fatal blow to the establishment of legitimate anti-Communist government in the South. Thiệu’s autocratic turn betrayed the constitutional order on which the state’s authority was based, deflating post-Tet enthusiasm, accelerating American funding cuts, and precipitating South Vietnam’s collapse from within during the final Communist offensive in 1975. Drawing on newly available Vietnamese-language sources, the chapter examines the underappreciated impact of a diverse range of Vietnamese protagonists, who shaped the decisive political breakdown that brought the Vietnam War to its conclusion.

At the prompting of the Nixon White House, President Nguyen Van Thieu sent South Vietnamese forces into Laos in February 1971, seeking to cut North Vietnamese supply lines to the battlefields in the South. Lam Son 719 was a bloody failure, and it shaped the final phase of America’s Vietnam War. Convinced that the South Vietnamese could never withstand a full-scale offensive, the North Vietnamese leadership committed to a nation-wide attack in early 1972, designed to bring a decisive end to the war. The Easter Offensive, as it is remembered in the West, broke on three fronts in late March 1972, initially with a series of victories by the NVA. President Richard Nixon and his national security advisor, Henry Kissinger, viewed this offensive as a threat to their political and diplomatic objectives, and ordered a massive deployment of US air and naval forces to reinforce the South Vietnamese. In May 1972, Nixon ordered an air offensive against North Vietnam code-named Linebacker to deny resupply to the North Vietnamese forces. The NVA offensive stagnated in late June, setting the stage for negotiations between the US and Hanoi to end the war. Kissinger and Le Duc Tho reached a settlement in early October, but it was rejected by Thieu, forcing the US to renegotiate the treaty. In the end, Nixon directed the most violent air campaign of the war, sending B-52 heavy bombers over Hanoi to coerce the North Vietnamese into accepting the minor changes required for a settlement.

Hanoi entered into negotiations with Washington and Saigon in 1968–9, Chapter 4 explains, but merely to probe and sow division among its enemies. But then unsettling circumstances intervened, including the Sino-Soviet Border War of early 1969; the death a few months later of Ho Chi Minh, who, despite his lack of influence over communist decision-making, remained the venerable face of the Vietnamese struggle for reunification and independence and thus an important public relations tool; and, finally, Nixon’s decisions to “Vietnamize” the anticommunist war effort in the South and then to authorize incursions into Cambodia and Laos. The period 1969–71 was marked by uncertainty and indecisiveness as communist decision-makers reassessed their strategic priorities and placed greater emphasis on alternative modes of struggle. Concerned about potential diplomatic isolation and the loss of Soviet and Chinese support, Le Duan decided to go-for-broke once more. The 1972 Easter Offensive was an abject disaster. Hanoi then tried its luck at the bargaining table, resulting in the Paris peace agreement of 1973 and the suspension of the Fourth Civil War for Vietnam.

Chapter 5 assesses US air power following the Tet Offensive through the cross-border incursion into Cambodia in 1970. The newly elected US president, Richard Nixon, sought an American withdrawal from South Vietnam. However, he initially expanded the conflict into Cambodia to deny the NVA/VC sanctuary and sever their southern supply lines. Leading up to the invasion, the Commando Hunt air interdiction campaign in southern Laos slowed the movement of supplies. It also imposed substantial costs on the North to keep the Ho Chi Minh Trail open. Commando Hunt could not halt the NVA troops from making the journey to South Vietnam on foot, but the direct attack of fielded forces in South Vietnam and Cambodia did continue to keep the NVA/VC dispersed and hidden. Keeping the North Vietnamese on the defensive provided the time and space for South Vietnam’s pacification program to take root and for the Vietnamization program to generate conventional capabilities for the Army of the Republic of Vietnam (ARVN) to replace withdrawing American combat troops.

Looking at the Korean and Vietnam Wars, we evaluate the influence of casualties disaggregated by space/hometowns and time on mass opinion in both the Korean and Vietnam wars and on individual opinion in the Vietnam War. We find a powerful connection between US casualties and public support for a war consistent with our expectations about the importance of casualty trends, the geographic locations of casualty hometowns, and the interaction of these dynamics. Disaggregated casualties are better able to capture variation in mass public and individual wartime opinion than are logged cumulative national casualties – the standard wartime measure employed. We also find that the wartime information-opinion process operates more strongly in the ex ante identifiable early stages of a conflict, and less effectively later in a conflict when casualty expectations (and thus the value of new information) begin to harden. These results strongly support the general notion that casualty patterns act as an observable proxy for our RP/ETC process by capturing information that individuals draw on to generate ETC and formulate wartime positions, improving our ability to understand and predict wartime opinion.