A key reason for the Vietnam War was North Vietnam's desire for national unification.
After Vietnam was divided in 1954 at the Geneva Conference, Ho Chi Minh led the North, while Ngo Dinh Diem ruled the South. Ho Chi Minh was a popular leader who had earlier fought against Japanese invaders and French colonial rule. He introduced land reforms by taking land from rich landlords and redistributing it to poor peasants. Although many fled South to escape harsh communist rule, these policies gained him strong support from the peasants who benefited. Ho Chi Minh and the Viet Minh aimed to reunify the country under communism. To achieve this, they encouraged armed struggle in the South through the Viet Cong, a communist guerrilla group. Many North Vietnamese saw reunification as a patriotic duty and supported Ho Chi Minh's cause. This determination to unite Vietnam by force was one of the main reasons the war began.
Another reason for the war was the corruption and unpopularity of the South Vietnamese government under Ngo Dinh Diem. Diem came to power after a rigged 1955 referendum that removed Emperor Bao Dai. Although elections were supposed to be held in 1956 to unify Vietnam, Diem cancelled them because he feared losing to Ho Chi Minh. Diem's rule was harsh, corrupt, and filled with nepotism. He gave powerful positions to his family members and favoured Catholics even though most Vietnamese were Buddhists. His anti-Buddhist policies caused outrage - monks protested and some even set themselves on fire in 1963. Diem also imprisoned and tortured thousands of suspected communists, driving many people in the South to join the Viet Cong. North Vietnam later supported these rebels through the Ho Chi Minh Trail, which transported weapons and supplies into South Vietnam. Diem's unpopularity thus weakened the South and made the communist movement stronger, leading to open conflict.
Another reason for the war was external involvement. The Chinese Communist Party (CCP) had won power in 1949 and wanted to spread communism in Asia. Mao Zedong saw Vietnam as an important buffer against the United States. He provided Ho Chi Minh with weapons, training, and political backing. This support gave North Vietnam the confidence to challenge the South militarily. The Soviet Union also supported North Vietnam, especially after its split with China in the 1960s. The Soviets supplied advanced weapons such as aircraft and air defence systems. Their backing helped North Vietnam resist U.S. bombing and strengthened its position in the war. The United States supported South Vietnam as part of its policy of containment, aimed at stopping the spread of communism in Asia. The U.S. initially sent military advisers and supplies through the Military Assistance Command Vietnam (MACV). However, after President John F. Kennedy's assassination in 1963, President Lyndon B. Johnson became more willing to commit troops. The turning point came in August 1964, when the Gulf of Tonkin Incident occurred. North Vietnamese patrol boats allegedly attacked a U.S. destroyer. Congress then passed the Gulf of Tonkin Resolution, giving Johnson full authority to use force in Vietnam. This marked the start of direct U.S. military involvement, escalating the conflict into a full-scale war.
In conclusion, the Vietnam War broke out because of a combination of internal and external factors. Ho Chi Minh's determination to unify Vietnam under communism and Diem's unpopular rule created tension within the country. At the same time, the involvement of major powers like China, the USSR, and the USA turned a local conflict into an international Cold War battleground. Together, these factors explain why the Vietnam War began.