In early March 1975, buoyed by a successful operation at the start of the year, Hanoi launched the first phase of an offensive to take the whole country.
The south Vietnamese army crumbled faster than expected, and in seven weeks communist forces had swept through the south taking the central highlands and the east coast. Millions of refugees fled towards Saigon.
On 21 April, with the NVA closing in on Saigon, the South Vietnamese President Nguyen Van Thieu resigned and fled to Taiwan, railing tearfully against the US.
Six days later the city was surrounded. The NVA began launching shells into civilian areas. Looting broke out.
On 29 April the US ordered the helicopter evacuation of 7,000 American administrators and South Vietnamese from the city. Refugees battled to join the exodus.
The following day, NVA tanks drove unopposed into central Saigon. The city was renamed Ho Chi Minh City.