The Battle of Đức Dục took place from 18 July to 4 October 1974 in Đức Dục District, Quảng Nam Province. The North Vietnamese made some minor territorial gains and suffered heavy losses, while South Vietnamese forces were severely weakened by the fighting.
Background Southwest of Đại Lộc District was the vast mountain district of Duc Duc. Only in the extreme northeast region of Duc Duc did South Vietnamese officials maintain full-time residence. The area west of the Thu Bồn River (Vietnamese: Sông Thu Bồn), which included part of the "Arizona Territory", was insecure and sparsely populated, as were the southern and western reaches of Đức Dục. Army of the Republic of Vietnam (ARVN) influence extended south to the Nông Sơn coal mines in the narrow canyon of the Thu Bồn River, about 10 kilometers from the district seat. Here at a place called Da Trach, not far north of the major operating base of the People's Army of Vietnam (PAVN) 2nd Division, the ARVN maintained a garrison with outposts manned by Regional Force (RF) units and Popular Force (PF) platoons. Đức Dục was the other principal entrance to the Quảng Nam lowlands from the PAVN-held highlands of Quảng Nam and Quảng Tín Provinces.
The ARVN 3rd Infantry Division was responsible for the defense of Quảng Nam and that part of Quảng Tín lying within the Quế Sơn Valley. In June 1974, General Nguyen Duy Hinh, the 3rd Division commander, had his 2nd Infantry Regiment operating in the Gò Nổi () and Đức Dục areas while the 78th Ranger Battalion held Da Trach.
Da Trach, a battalion-sized camp, was a strongpoint situated on a prominent hill about above the Thu Bồn River south of the subsector headquarters at Đức Dục. It had been quiet at Da Trach and around the outposts manned by one RF company and seven PF platoons. Three of these outposts were in the hills and along the river south of Da Trach, while the others were in the valley of the Khe Le stream (), which flowed into the Thu Bồn River northeast of Da Trach post. Also located in the valley was the 4th Company, 146th RF Battalion, which had its 80-man garrison in the Ap Ba hamlet group (), along the road that twisted eastward over the Deo Le Pass to Quế Sơn. Possession of the Khe Le Valley would give the PAVN not only another flanking approach to the ARVN defenses in the Quế Sơn Valley but would provide access to the several good trails into Duy Xuyên District, bypassing the defenses in Đức Dục.
The 78th Ranger Battalion at Da Trach, with about 360 men, was scheduled for retraining at the Ranger Training Center, and on 17 July 1974, the 3rd Battalion, 56th Infantry, arrived to execute the relief. The infantry battalion pulled in on trucks just before dark. The relief was to take place at noon the next day, but the 78th had withdrawn most of its outposts and was bivouacked for the night in the village. Although unfamiliar with the layout of the camp defenses, the 3rd Battalion, with three of its four companies, assumed the responsibility. The strength of the 3rd Battalion, 56th Infantry, was only about 360 men, but its 2nd Company was not in the camp; rather, it had set up outposts on two hills along the east bank of the Thu Bồn River. One rifle platoon was on Cua Tan Mountain() directly across the river from Da Trach, and the rest of the company was at Khuong Que (), to the north.
PAVN Military Region 5 was responsible for all of Quảng Nam Province to the Kon Tum Province boundary, its campaign plan for the summer and autumn of 1974 involved elements of three regular divisions, a separate infantry brigade, and several independent regiments. Objectives ranged from central Quảng Nam to southern Quảng Ngãi Provinces. To cope with the tactical and logistical requirements of this offensive, the PAVN leadership activated a new headquarters, the 3rd Corps. Operational in June, the corps began concentrating resources for the Quảng Nam campaign. The 36th Regiment was formed in the spring of 1974 from replacement groups sent from North Vietnam into the mountains of western Đức Dục. It was a light regiment, having only two infantry battalions, an antiaircraft machine gun company, light artillery, and administrative support units. On 10 July, a week before the planned relief of the 78th Ranger Battalion at Da Trach, the 36th Regiment moved undetected into assembly areas close to ARVN outposts around Da Trach. Also on the move toward Da Trach were elements of all three regiments of the 2nd Division, the 1st, 31st, and 38th, plus the 10th Sapper Battalion, division artillery, and batteries of Military Region 5 artillery.
Battle Shortly after midnight on 18 July, PAVN artillery, rockets and mortar rounds began exploding on the defenses and outposts of Da Trach. A relatively weak attack by the PAVN 2nd Battalion, 36th Regiment, on the camp's main defenses was beaten back with heavy losses to the PAVN and light casualties to the defenders, but contact with the 2nd Company, 3rd Battalion, 56th Infantry, outposts at Khuong Que and Cua Tan was lost before daybreak. By that time, the 4th Company, 146th RF Battalion at Ap Ba had been attacked and overrun, and the survivors were trying to escape through the mountains toward Đức Dục headquarters. Shelling of the main camp meanwhile had stopped, and the attackers regrouped for another assault. The 2nd Battalion, 1st Infantry Regiment and a battalion of the 31st Infantry Regiment, joined the two battalions of the 36th Regiment for the next attempt. As the reconnaissance platoon and the 4th Company, 3rd Battalion, 56th Infantry, tried to retake a lost outpost south of the camp, they were stopped by intense artillery and automatic weapons fire, which killed the company commander and the battalion commander of the 78th Rangers. The PAVN resumed infantry assaults on the camp, and the 3rd Battalion commander, who had assumed command of the 78th Rangers as well, reported the situation critical. The camp's radio was knocked out before noon, and all contact was lost with whatever PF outposts remained in action. Simultaneously with their assault on Da Trach, the PAVN began the Battle of Thượng Đức to the northwest, stretching the ARVN forces in the area.
PAVN tanks were sighted about 5 km southwest of the camp, and the Republic of Vietnam Air Force (RVNAF) began to provide air support to the defenders. Heavy artillery, rocket, and mortar fire continued, augmented by antiaircraft guns, up to 37 mm, used in direct fire. Contact was also lost with the 4th Company, 78th Rangers, and the two-gun platoon of 105 mm howitzers in the camp had been knocked out of action. At mid-afternoon, the five-battalion PAVN assault, which by this time included the 10th Sapper Battalion against the northern sector, had carried through the southwest defense line. With all bunkers and fighting positions demolished by a bombardment of more than 5,000 rounds, the survivors of the 3rd and 78th Battalions withdrew and the PAVN rounded up civilians in the hamlets and villages; about 7,500 of them would be moved to PAVN controlled regions of Đức Dục District.
Hinh moved a forward division command post to Đại Lộc and ordered the 2nd Infantry Regiment to deploy immediately to Đức Dục and relieve the defenders at Da Trach. Operation Quang Trung 4/74 had begun. Only the 3rd Battalion, 2nd Infantry, was immediately available; the 1st Battalion remained at Firebase Baldy in the Quế Sơn Valley, and the 2nd was still in Quảng Tín Province. Orders were sent to both battalions to move immediately to Đại Lộc District, and the 3rd Battalion moved from Da Nang to Hill 55 in northwestern Điện Bàn District to protect the deployment of artillery to support Đức Dục.
Hinh saw as his first priority securing the bridge over the Thu Bồn River, north of Đức Dục base and over which all division elements would have to pass en route to the battlefield. He ordered the 1st Battalion, 2nd Infantry, just arrived from Firebase Baldy, with the 2nd Troop, 11th Armored Cavalry, to secure the bridge and had the 3rd Battalion, 2nd Infantry, on 18 July move to Đức Dục base. His staff went to work immediately drafting the tactical plan for Quang Trung 4/74 with the objective of retaking Da Trach. The bridge secured, the 1st Battalion joined the 3rd, and both moved south of Đức Dục, prepared to continue on toward Da Trach. By nightfall on the 18th, the 2nd Battalion, 2nd Infantry, had also moved to Đức Dục base, as had a battery of 155 mm howitzers. Meanwhile, a battery of 175 mm guns moved into firing positions in the Quế Sơn Valley, within range of Đức Dục. These ARVN artillery positions soon received heavy and accurate counterbattery fire. The commander of the 2nd Infantry, Lieutenant colonel Vu Ngoc Huong, having assumed tactical command of all ARVN forces in the Đức Dục-Da Trach battlefield, had communications with only two platoons of the original Da Trach defense force by the evening of 18 July.
The PAVN resumed its coordinated offensive in Quảng Nam in the pre-dawn hours of 19 July. A salvo of 35 122 mm rockets fell on Da Nang Air Base, damage to RVNAF operations was slight, although 16 people died and over 70 were wounded many of whom were civilians and military dependents. In the morning Đức Dục received 45 rocket and mortar rounds. PAVN 130 mm guns hit an ARVN 105 mm battery and the 2nd Infantry's command post. Meanwhile, north of Đại Lộc on Route 540, the 370th RF Company repulsed a strong enemy attempt to interdict the ARVN line of communication, killing 30 of the attackers and capturing many weapons.
With the PAVN fire erupting in their rear, the 1st and 3rd Battalions, 2nd Infantry, advanced south from Đức Dục toward Da Trach and by noon reported securing their initial objectives without opposition. The 1st Battalion was on Ky Vi Mountain (), southeast of Đức Dục base, and the 3rd Battalion was on Hill 284 (), past Khuong Que and at the entrance of Khe Le Valley. The 2nd Battalion was in reserve. The plan called for the 3rd Battalion to continue the attack to Cua Tan Mountain, across the river from Da Trach, and for the 1st Battalion to attack south, first seizing Hill 454 () and then descending into the Khe Le Valley at the village of Ap Ba. The feasibility of the plan came into question, however, when the last contact with the Da Trach defenders on 19 July revealed that the command group and two companies of the 78th Rangers were under heavy attack on the hill at Cua Tan.
After seizing Da Trach, the PAVN placed infantry battalions and antiaircraft guns in the hills above the valley, awaiting the arrival of the ARVN 2nd Infantry. The RVNAF struck hard at these forces on the 18th and 19th and caused heavy casualties, but the PAVN could not be dislodged. By the afternoon of 19 July, the 1st Battalion, 2nd Infantry was in contact with elements of the PAVN 36th Regiment on Ky Vi Mountain and on Hill 238 (), to the west. The RVNAF flew 18 attack sorties in support, killing 75 PAVN infantrymen and destroying a mortar, but the ARVN advance had to be halted. Suspecting a trap in the Khe Le Valley, Hinh ordered the 2nd Infantry to stop and sent reconnaissance patrols forward.
Correctly anticipating that the PAVN's Quảng Nam campaign had only begun and that more forces would be required to deal with it, I Corps commander General Ngô Quang Trưởng on 19 July ordered the 12th Ranger Group to move from Quảng Ngãi to Quảng Nam. The 37th Ranger Battalion, already in Da Nang for rest and retraining, moved to Hieu Duc District on 20 July. That day, the 6th Infantry, 2nd Division, began relieving the other two battalions of the 12th Ranger Group in Đức Phổ and Mộ Đức Districts in Quảng Ngãi Province, and the 12th began to move north.