Units of South Vietnam's 9th and 21st Divisions, along with several South Vietnamese airborne battalions, open new stretches of road south of An Loc and come within two miles of the besieged city. In the Central Highlands, North Vietnamese troops, preceded by heavy shelling, tried to break through the lines of South Vietnam's 23rd Division defending Kontum, but the South Vietnamese troops held firm. These actions were part of the North Vietnamese Nguyen Hue Offensive (later called the "Easter Offensive"), a massive invasion by North Vietnamese forces on March 30 to strike the blow that would win them the war. The attacking force included 14 infantry divisions and 26 separate regiments, with more than 120,000 troops and approximately 1,200 tanks and other armored vehicles. The main North Vietnamese objectives, in addition to Quang Tri in the north and Kontum in the Central Highlands, included An Loc farther to the south.
Initially, the South Vietnamese defenders were almost overwhelmed, particularly in the northernmost provinces, where they abandoned their positions in Quang Tri and fled south in the face of the enemy onslaught. At Kontum and An Loc, the South Vietnamese were more successful in defending against the attacks, but only after weeks of bitter fighting. Although the defenders suffered heavy casualties, they managed to hold their own with the aid of U.S. advisors and American airpower. Fighting continued all over South Vietnam into the summer months, but eventually the South Vietnamese forces prevailed against the invaders and retook Quang Tri in September. With the communist invasion blunted, President Nixon declared that the South Vietnamese victory proved the viability of his Vietnamization program, which he had instituted in 1969 to increase the combat capability of the South Vietnamese armed forces.