South Vietnamese troops from the 21st Division, trying to reach beleaguered An Loc in Binh Long Province via Highway 13, are again pushed back by the communists, who had overrun a supporting South Vietnamese firebase. The South Vietnamese division had been trying to break through to An Loc since mid-April, when the unit had been moved from its normal area of operations in the Mekong Delta and ordered to attack in order to relieve the surrounded city. The South Vietnamese soldiers fought desperately to reach the city, but suffered so many casualties in the process that another unit had to be sent to actually relieve the besieged city, which was accomplished on June 18.
This action was part of the southernmost thrust of the three-pronged Nguyen Hue Offensive (later known as the "Easter Offensive"), a massive invasion launched 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 An Loc in the south, were Quang Tri in the north and Kontum in the Central Highlands. Initially, the South Vietnamese defenders in each case were almost overwhelmed, particularly in the northernmost provinces, where government forces abandoned their positions in Quang Tri and fled south in the face of the enemy onslaught.
In Binh Long Province, the North Vietnamese forces had crossed into South Vietnam from Cambodia on April 5 to strike first at Loc Ninh. After taking Loc Ninh, the North Vietnamese forces then quickly encircled An Loc, the capital of Binh Long Province, which was only 65 miles from Saigon. The North Vietnamese held An Loc under siege for almost three months while they made repeated attempts to take the city. The defenders suffered heavy casualties, including 2,300 dead or missing, but with the aid of U.S. advisers and American airpower, they managed to hold An Loc against vastly superior odds until the siege was lifted on June 18. Fighting continued all over South Vietnam into the summer months, but eventually the South Vietnamese forces prevailed against the invaders and they 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.