On April 3, 1975, in Khanh Hoa, after the victory in liberating Nha Trang Town, the 10th Division and local armed forces advanced to liberate the Cam Ranh Joint Military Zone — an important enemy naval base.
In Da Lat, after liberating Duc Trong, liberation forces continued to advance to liberate Da Lat Town, the last and very important enemy stronghold in the Central Highlands.
At 3:00 a.m. on April 3, 1975, the forces reached the Phi Nom junction and divided into two groups: Battalion 840, Regiment 812, while the main force of Military Region 6, advanced along Route 21 to D’Ran Town.
The enemy troops there had fled, the unit quickly took over the sub-region, the district capital, and established the Don Duong District Military Management Committee.
Battalion 186 followed Route 20 to Da Lat. At 8:00 a.m. on April 3, 1975, the unit arrived at the Kim Cuc gas station intersection, the gateway to Da Lat, and met some of liberation grassroots cadres.
A squad of the battalion, together with cadres and grassroots Da Lat, advanced to occupy the provincial administrative building of the puppet government.
At 8:20 a.m. on April 3, 1975, the revolutionary flag flew at the headquarters of the puppet provincial government, marking the complete liberation of Da Lat Town and Tuyen Duc Province.
As such, on April 3, 1975, the two southern provinces of the Central Highlands, Tuyen Duc and Lam Dong, were completely liberated. On April 3, 1975, the Central Highlands campaign ended with complete victory, far exceeding initial expectations.
During 30 days of continuous attacks, liberation forces destroyed and disintegrated the 2nd Army Corps of the Republic of Vietnam, a strategic reserve unit of the enemy, along with all enemy forces in the Central Highlands and the two provinces of Phu Yen and Khanh Hoa.
On April 3, 1975, at the Command Headquarters east of La Nga Bridge, the Party Committee and the Command of the 4th Army Corps discussed a plan to capture Xuan Loc Town — a strong defensive area of the enemy, known as the “steel door” on the eastern gateway to Saigon.
The adopted combat plan was to use a large force of infantry, tanks, and artillery to attack directly at the Sub-Region Command and Division 18, quickly occupy Xuan Loc, creating a position and force for the Liberation Army to attack and approach Bien Hoa, Ba Ria-Vung Tau.
From April 1 to 3, 1975, in coordination with other military wings, naval units participated in the attack on the Quy Nhon, Nha Trang, and Cam Ranh bases.
The sea attack force included 3 missile boats of Battalion 173 (Regiment 172), 4 combat patrol boats of Regiment 171, and the military transport force of Group 125, causing the enemy to panic and waver, reducing support and assistance activities at sea.
On the Truong Son strategic support route, on the same day of April 3, 1975, the second formation of 395 vehicles of the 515th Automobile Regiment, a part of the 13th Automobile Regiment of the Truong Son Command, mobilised the 312th Division and the 1st Corps agency along the Eastern Truong Son route to the South.
On the same day, the Frontline Department marched to the location of the Regional Command and the Central Office for the South at the Loc Ninh base. For the northern rear, in the first two months of 1975, the north mobilised 57,000 troops (out of a total of 108,000 troops of the 1975 mobilisation plan); urgently trained and supplemented the battlefield.
Many delegations of cadres from Party agencies and the Ministry of National Defence: the General Staff, the General Department of Politics, the General Department of Logistics, the General Department of Engineering and military branches urgently entered the battlefield to urge preparations.
