South Vietnamese army forces invade southern Laos. Dubbed Operation Lam Son 719, the mission goal was to disrupt the communist supply and infiltration network along Route 9 in Laos, adjacent to the two northern provinces of South Vietnam.
The operation was supported by U.S. airpower (aviation and airlift) and artillery (firing across the border from firebases inside South Vietnam). Observers described the drive on North Vietnam's supply routes and depots as some of the bloodiest fighting of the war. Enemy resistance was initially light, as a 12,000-man spearhead of the South Vietnamese army thrust its way across the border into the communists' deepest jungle stronghold--the town of Tchepone, a major enemy supply center on Route 9, was their major objective. However, resistance stiffened in the second week when the North Vietnamese rushed reinforcements to the area. During the last week of February, the big push bogged down about 16 miles from the border, after bloody fighting in which the communist troops overran two South Vietnamese army battalions.
Also on this day: In Cambodia, Premier Lon Nol suffers a paralyzing stroke and turns his duties over to Deputy Premier Sirik Matak. Debilitated by the stroke, Lon Nol resigned on April 20. A week later, he withdrew his resignation, staying on in a figurehead role as Sirik Matak continued to run the government pending his recovery.