On the night of 28 May 1965, the VC marched into their designated positions around Ba Gia; the 90th Battalion took up their position at Minh Thành, the 60th Battalion at Vĩnh Lộc, the 40th Battalion at Duyên Phước, and the 45th Battalion at Vĩnh Khánh. The 1st Regimental Headquarters set up camp at Mount Hốc Khoai, At 09:50, as the ARVN 1st Battalion marched through Lộc Thọ village they were encircled by the VC 90th Battalion, who had set up ambush positions in Mount Khỉ and were waiting for the ARVN to arrive. Caught by surprise, the ARVN 1st Battalion descended into chaos and was unable to mount an effective counter-attack. In less than one hour of fighting, the battalion was completely destroyed with 270 soldiers either killed or wounded. Ngọc was amongst the 217 men who were captured. Only 65 ARVN soldiers and three American advisors managed to return to government lines. The VC also claimed to have destroyed one 105mm artillery piece, four GMC trucks and one Jeep. Meanwhile, the VC 83rd Local Force Battalion marched from
Trà Khúc River toward
Nghĩa Hành District, and began applying pressure on the ARVN stationed there. Thus, the VC were asserting control over Ba Gia and the surrounding areas. On the afternoon of 29 May, Thi responded to the VC assault by forming a Task Force with the objective of recapturing Ba Gia. The Task Force consisted of the 2nd Battalion, 51st Infantry Regiment, the 3rd Marine Battalion, the 39th Ranger Battalion and one squadron of
M113 armored personnel carriers. According to Thi's plan, the Task Force would achieve the following objectives: the 3rd Marine Battalion would advance along Route 5 toward the objective of Ba Gia; the 39th Ranger Battalion through An Thuyết, Vĩnh Lộc and Vĩnh Khánh and then capture Mount Chóp Nón; and the 2nd Battalion, 51st Infantry Regiment towards Phước Lộc and capture Mount Mả Tổ. On the morning of 30 May the South Vietnamese Task Force assembled in Quảng Ngãi town and waited for further orders, while ARVN artillery and U.S. Air Force fighter-bombers pounded VC positions around Ba Gia. At around midday on 30 May, with extensive air support from U.S. fighter-bombers and
UH-1 helicopter gunships, the ARVN advanced towards their objectives in two separate columns. In the first, the ARVN 39th Ranger Battalion approached northern Phước Lộc to secure Mount Chóp Nón, from where they could strike at the VC's southern flank. In the second column the ARVN 2nd Battalion and the 3rd Marine Battalion advanced towards their objectives of Mount Mả Tổ and Ba Gia respectively. However, South Vietnamese manoeuvres on the ground did not go unnoticed, because VC reconnaissance teams on Mount Khỉ had spotted the columns and responded accordingly. Elements of the VC 45th Battalion were ordered to set up ambush positions inside the village of Vĩnh Khánh, while the 60th Battalion was redeployed to Mount Mả Tổ and waited for the enemy there. At about 13:00 the ARVN 2nd Battalion, 51st Infantry Regiment arrived on Hill 47 in the vicinity of Mount Mả Tổ, but the VC 60th Battalion allowed them to advance toward their objective. Meanwhile, the ARVN 39th Ranger Battalion secured their objective on Mount Chóp Nón, with the main formation of the VC 45th Battalion lining their troops on the rear positions of the ARVN Rangers. At 14:00, VC artillery began bombarding the 39th Ranger's position and also targeted the task force’s artillery at Ba Gia to make it difficult for the howitzers to support the rangers. Allied fighter-bombers responded quickly, but were unable to strike because the airborne
Forward air controller could not locate the battle. Meanwhile, the fighting between the rangers and the VC 45th Battalion became fierce, swinging back and forth over the course of the day. As the pressure on the rangers grew, the task force commander ordered the 2nd Battalion, 51st Infantry, to move north from Phước Lộc to help. The 3rd Marine Battalion would advance to occupy the village in place of the infantry. The 2nd Battalion responded slowly, with the result that both battalions were still in and around Phước Lộc when the VC attacked at 16:00. Again, the fighting was ferocious. The VC 40th Battalion overran one infantry platoon and forced the rest of the 2nd Battalion to consolidate on a hill west of town. The VC 60th Battalion drove the 3rd Marine Battalion out of the village, with the marines taking shelter in a moat on the north side of the town. Allied airpower helped prevent the VC from overrunning these positions and ultimately facilitated the withdrawal of the 2nd Battalion, 51st Infantry, and the M113 troop. Nightfall found the marines holding the moat for a length of about 400 meters. During the night, the VC launched numerous probes and three major assaults against them. In each case, the marines held their fire to the last minute, then shifted their position within the moat after each attack. Their tactics succeeded, but the 39th Ranger Battalion on Mount Chóp Nón was not as fortunate. Overnight, the VC ravaged the battalion except for one company that survived. By dawn on 31 May, the VC had begun to withdraw. ==Aftermath==