The action of 1 March 1968 was a co-ordinated attempt by four North Vietnamese trawlers to resupply the Viet Cong and the efforts of Operation Market Time elements to stop them during the Vietnam War. On 28 February 1968, United States Navy SP-2H Neptune aircraft on routine patrol detected a North Vietnamese SL class naval trawler heading towards the South Vietnamese coast from north of the DMZ. By the next morning, three more trawlers were discovered and units of Operation Market Time were deployed for a surprise interception. The suspect trawlers did not fly flags so it was not until the start of the engagement that their origin was discovered. The trawlers were steel-hulled vessels, 100 feet long and armed with 57-millimeter recoilless rifles and machine guns. All four vessels were loaded with weapons and ammunition intended to be delivered to the Viet Cong. American and South Vietnamese forces that engaged in action included the United States Coast Guard cutters Androscoggin, Point Grey, Point Welcome, Winona, Point Grace, Point Hudson, Point Marone, the swift boats USS PCF-18, USS PCF-20, USS PCF-42, USS PCF-43, USS PCF-46, USS PCF-47 and USS PCF-48, two South Vietnamese navy junks and one patrol boat. Two U.S. Army helicopter gunships also participated in combat as well as aircraft used to fire flares.

Operation Market Time was the United States Navy, Republic of Vietnam Navy and Royal Australian Navy operation begun in 1965 to stop the flow of troops, war material, and supplies by sea, coast, and rivers, from North Vietnam into parts of South Vietnam during the Vietnam War. Also participating in Operation Market Time were United States Coast Guard's Squadron One and Squadron Three. The U.S. Coast Guard operated, under U.S. Navy command, heavily armed 82-foot (25 m) patrol boats and large cutters armed with 5-inch naval guns, which were used in battle and gunfire support.