North Vietnamese Troops In Quang Tri, May 1972. Source: People’s Army Newspaper website
On 1st May 1972, PAVN forces broke into the provincial capital of Quang Tri, capturing the city, causing a precipitate flight of the defeated garrison down Highway 1 towards Hué and almost leading to the collapse of the entire ARVN front line. This was the high point of North Vietnam’s Easter Offensive. Only heavy US bombing managed to slow the NVA advance and give time to South Vietnamese forces to regroup.
In retaliation, on 8th May, Nixon ordered a resumption of the bombing of towns and cities in North Vietnam, including, controversially, the mining of the harbour of the city of Haiphong, aiming to squeeze the DRV economically by restricting imports and exports to and from North Vietnam’s only major commercial port.