After the abrupt removal and assassination of President Ngô Đình Diệm by General Dương Văn Minh's military junta, Nguyễn Ngọc Thơ was appointed to lead the South Vietnamese government. Thơ, who had served as Interior Minister, was tasked with steering the country through an exceedingly volatile period marked by widespread discontent and insurgency. The coup against Diệm was fueled by various factors including dissatisfaction with his oppressive regime and the increasing influence of the communist movement in the region. Thơ's appointment was an attempt by the junta to present a more moderate face to both the Vietnamese populace and the international community, particularly the United States, which had supported Diệm's government despite its controversial practices.

Thơ's leadership was under scrutiny from the outset, as he inherited numerous issues including internal divisions and an escalating conflict with North Vietnam. The political scene in South Vietnam was fragmented, with various factions vying for power and influence, complicating any efforts for a cohesive government. There were hopes that Thơ could unify these factions and restore some degree of order in the nation. However, he faced significant challenges, both from military opposition and civil unrest, which continued to undermine efforts for stability. Furthermore, his government had to deal with the increasing pressure from the National Front for the Liberation of South Vietnam, or Viet Cong, which was gaining public support against the regime.

Thơ's tenure was relatively short-lived and marked by continued instability. Although he was seen as a more approachable leader compared to his predecessor, the ingrained issues within South Vietnamese society and the political landscape posed significant obstacles. His ability to navigate these challenges would define his effectiveness as a leader in a time of crisis and set the stage for further changes in governance in South Vietnam during the ongoing conflict with the North.