After the French defeat at Dien Bien Phu (1954), ceasefire and partition of Vietnam ended First Indochina War. Vietnam north of the 17th parallel known as Democratic Republic of Vietnam, with capital in Hanoi; Vietnam south of that line known as the Republic of Vietnam (ROVN); figleaf for continued Western colonial rule.
DRV initially hoped to reunite Vietnam in accordance with the terms drawn up by 1954 Geneva Agreements, but Ngo Dinh Diem and his CIA handlers set about purging Communists in South Vietnam. So in 1959, PAVN began preparations for infiltrating South Vietnam (Ho Chi Minh Trail).
In 1968, PAVN launched offensive against ROVN; disaster, loss of non-Communist allies in the South. Rebuilt with surprising speed, despite massive US bombing ("Rolling Thunder"). In 1972, offensive reduced ROVN control to small enclaves in the South. Increased US bombing ("Linebacker") of DRV, while US Army sought to train the Army of ROVN (ARVN). US troops withdrawn March 1973, resulting in collapse, PAVN victory.
In Dec 1978, after attacks by Khmer Rouge PAVN invaded and liquidated genocidal regime of Pol Pot in Cambodia. Khmer Rouge ally, China, invaded Vietnam March 1979, but PAVN defeated invasion.
Their most famous commander is Vo Nguyen Giap (1911-).