After the Tay Nguyen Campaign was expanded to achieve success on March 20, 1975, Regiment 271 liberated Kien Duc (now the centre of Dak R’Lap District in the Central Highlands province of Dak Nong).
On the same day, under the direction of the Regional Command, the Binh Phuoc armed forces temporarily halted their match to liberate Gia Nghia and urgently turned back. From the direction of Bu Dop, they marched down to surround Binh Long so that the Binh Long forces could descend to encircle Chon Thanh.
In northeastern Saigon on the afternoon of March 20, after 4 days of fighting, Division 7 and local forces had destroyed and disintegrated the entire enemy force, including parts of the enemy Division 18 sent as reinforcements, controlling a section of over 50km of Highway 20, cutting off the only road from the southeastern region to the Central Highlands, opening up another important corridor for the Liberation Army in the northeastern direction of Saigon.
On the outer ring of Saigon’s periphery on March 20, Gia Dinh Regiment 1, in conjunction with Cu Chi local troops, attacked a GMC convoy carrying ammunition on the Hoc Mon-Cu Chi route. Special forces joined the second Special Forces Division to deploy to the southwest, shelling Bien Hoa Airport and Dong Du.
On the An Loc-Chon Thanh route on March 20, 1975, Corps 4 used a portion of Division 9 and Regiment 341 in conjunction with the local Binh Phuoc forces to attack and liberate the towns of An Loc and Chon Thanh, eliminating over 2,000 puppet soldiers.
On the same day, the General High Command sent a telegram praising the fighting spirit of the Tri-Thien Military Region for successfully completing the task of completely liberating the central province of Quang Tri. It informed them that the enemy could withdraw from Thua Thien-Hue to regroup at strategic key points and instructing them to: Continue the offensive, you are not permitted to stop at My Chanh; concentrate on using two regiments (4, 46) to form an offensive spearhead from the North, combine with the second Corps from the South to attack and destroy the enemy in Hue and block the Thuan An Seaport to prevent the enemy from retreating by sea.
