The Vietnam War was a conflict between the Democratic Republic of Vietnam (DRVN, or North Vietnam), allied with the Communist World, namely the Soviet Union and China against the Republic of Vietnam (RVN, or South Vietnam), and its allies — notably the United States military in support of the South, with US combat troops involved from 1965 until the official withdrawal in 1973. After France's attempted recolonization of Vietnam was defeated in 1954 by the Viet Minh, an agreement to temporarily partition the country in two with a de-militarized zone (DMZ) was reached at the Geneva Conference (1954). The Vietnam War ostensibly began as a civil war between feuding governments. Being Western-oriented and perceived as less popular than Ho Chi Minh’s northern government, the South Vietnam government fought largely to maintain its governing status within the partitioned entity, rather than to "unify the country" as was the goal of the North. Fighting began in 1957 and with U.S. and Soviet-Chinese involvement would steadily escalate and spill over into the neighboring Indochinese countries of Cambodia and Laos.
The Geneva partition was not a natural division of Vietnam and was not intended to create two separate countries. But the South government, with the support of the United States, blocked the Geneva scheduled elections for reunification. In the context of the Cold War, and with the recent Korean War as a precedent, the U.S. had feared that a reunified Vietnam would elect a Communist government under the popular Ho Chi Minh, either freely or fraudulently.
Western allies portrayed the conflict as based in a principled opposition to communism —to deter the expansion of Soviet-based control throughout Southeast Asia, and to set the tone for any likely future superpower conflicts. The North Vietnamese government and its Southern dissident allies (NLF) viewed the war as a struggle to reunite the country and to repel a foreign aggressor —a virtual continuation of the earlier war for independence against the French.
After fifteen years of protracted fighting and massive civilian and military casualties, major direct U.S. involvement ended with the signing of the Paris Peace Accords in 1973. Fighting between Army of the Republic of Vietnam (ARVN) forces against the dominant combined People's Army of Vietnam (PAVN) and NLF forces would soon bring an end to the RVN and the war on April 30, 1975. With the Northern victory, the country was reunified as the Socialist Republic of Vietnam (SRV) with a communist-controlled government based in Hanoi.