The lead-up to the Battle of Kontum began in mid-1971, when North Vietnam decided that their performance in Operation Lam Son 719 indicated that the time had come for large-scale conventional offensives that could end the war quickly. The resulting offensive, planned for the spring of 1972, would be known as the Easter Offensive in Western media, the 1972 Spring–Summer Offensive () in North Vietnam, or the Fiery Red Summer () in South Vietnam. The Easter Offensive would make use of fourteen divisions and would be the largest in the war.
The 1972 Easter Offensive began with a massive attack on the Demilitarized Zone with 30,000 People's Army of Vietnam (PAVN) soldiers and more than 100 tanks. Two thrusts of equivalent size, one towards Saigon and another to the Central Highlands and provincial capital of Kontum began soon after, code-named as Nguyễn Huệ campaign and Bắc Tây Nguyên campaign respectively. The North Vietnamese knew that if they could capture Kontum and the Central Highlands, they would cut South Vietnam in half.
The Battle for Kontum would pit the Army of the Republic of Vietnam (ARVN) 22nd Division, two Armored Squadrons (14th and 19th), the 2nd Airborne Brigade and the 2nd Ranger Group under Lt. Gen. Ngô Du in Phase I at Đắk Tô/Tân Cảnh; and later the 23rd Division, two Armored Squadrons (8th and 3rd), and two Ranger Groups (2nd and 6th) under Maj. Gen. Nguyễn Văn Toàn in Phase II at Kontum city, against the PAVN corps-size force of two regular divisions (320th and 2nd), two Artillery Regiments (40th and 675th), the 297th Tank Battalion, the 29th B-72 Missle Company plus B3 Front's four independent regiments (24B, 28th, 66th, 95B), and local Viet Cong forces under commander Maj. Gen. Hoàng Minh Thảo and commissar Trương Chí Cương.
There were two factors that persuaded North Vietnam that all out assaults of this kind could be successful. First, due to President Nixon's Vietnamization policy, there were no American divisional forces in the Central Highlands, only advisers and U.S. aviation units including Air Cavalry helicopter units from the 7/17 Air Cavalry Squadron. By June of that year there were less than 50,000 U.S. forces in all of Vietnam.
Second, the North Vietnamese had persuaded the Soviets and Chinese to provide 400 PT-76, T-34-85, T-54, and Type 59 tanks before the spring offensive.
Background North Vietnam had been using the Ho Chi Minh Trail along the border as a logistical artery for years. The mountainous terrain and the jungle were a shield against American air attack.
The ARVN bases at Tân Cảnh and Đắk Tô, were protected by the 42nd Regiment of the 22nd Division. The 22nd Division also controlled five fire support bases (FSBs) that stretched south-west from Tân Cảnh towards Kontum along a backbone of mountains nicknamed Rocket Ridge.
John Paul Vann, the civilian "general" of II Corps, had received intelligence that a major battle was coming. Du responded by moving the 22nd Division Forward CP, its 47th regiment, and a substantial logistic element of the division from their rear base in Bình Định province to the Đắk Tô/Tân Cảnh area. Elements of the 19th Armored Squadron were attached to the Division to support its organic 14th Armored Squadron equipped with M41 light tanks. The armored units would be deployed forward at Ben Het Camp which was regarded as the most likely direction of a PAVN armored attack. The movement was accomplished on 8 February. Vann also ordered increased B-52 air attacks that February and March.
Attacks on the Fire Support Bases On March 30, commander of the PAVN 320th Division, ordered his 52nd Regiment (Tây Tiến) to begin encircling and pressuring the ARVN 2nd Airborne Battalion and several nearby isolated outposts held by the 3/47th Infantry Battalion on Firebase Delta (Hill 1049). Facing intense pressure from three sides, the defenders were forced to contract their perimeter. On 3 April, the 52nd Regiment shifted to an offensive posture, inflicting heavy losses on the 2nd Airborne.
On 4 April 1972, the PAVN launched an early morning attack against Firebase Delta. Instead of the usual artillery fire from the jungle, elements of the PAVN 320th Infantry Division made a massed attack supported by artillery and rockets. For several days the PAVN hit FSB Delta and the other fire support bases along Rocket Ridge. Helicopters from the 52nd Combat Aviation operating out of Camp Holloway in Pleiku, were dispatched to provide support. The firebases were totally dependent on helicopter support for supplies and ammunition and in spite of the heavy anti-aircraft fire, the helicopters went on the offensive to provide fire support to the FSBs. At one point, the northern part of Delta was overrun by elements of the 320th Division. Vann, already in the area for an air rescue, was able to direct attacks on the PAVN soldiers entering the base with Cobra gunships. The PAVN attack was stopped in its tracks.
In the first week of April, Gen. Du's order of battle showed the 22nd Division with a total of 13 battalions consisting of three border ranger battalions, eight ARVN infantry battalions and scout companies, cavalry, sector forces, and 50 tubes of artillery; the Airborne Division with six airborne battalions, one border ranger battalion, and 16 tubes of artillery; Kontum sector with a ranger group of two battalions and territorial forces; and 50 tanks belonging to the 14th and 19th Armored Squadrons spread between Pleiku and Ben Het.
This realignment strained the logistical support of ARVN forces north of Vo Dinh due to the limited capability of the single road into the area. As this posture the ARVN forces were extremely vulnerable to an envelopment which would isolate al forces north of Vo Dinh. The pressure continued to increase, however, as the enemy buildup continued. His problems were compounded by the ineffective leadership of Col. , the 22nd Division Commander, whose inept handling of a combat assault by the 9th Airborne Battalion resulted in the loss of two helicopters, a failure to exploit two B-52 strikes, and divisiveness between the 22nd Division ann the Airborne Division.
On 14 April, following a rocket and artillery barrage, the 320th Division attacked Firebase Charlie (, Hill 1015) on the northern end of Rocket Ridge and 10 km from Đắk Tô. Despite airstrikes and helicopter gunship support the ARVN Airborne defenders were forced to abandon the base that night. Major John J. Duffy, the advisor to the 11th Airborne Battalion, would be awarded the Medal of Honor for his actions in 2022. The attacks on the firebases continued as April wore on. Finally on 21 April, FSB Delta was taken by the PAVN. Several of the other bases had to be given up soon after with heavy casualties.
Loss of Tân Cảnh and Đắk Tô
Since the start of the Easter Offensive at the end of March, the base areas had come under increasing PAVN artillery and rocket fire, which had gone from 20 to 50 rounds per day in March to up to 1000 per day by mid-April. During early April, the 47th Regiment withdrew to Đắk Tô II, while the 42nd Regiment and one Battalion of the 41st Regiment were at Tân Cảnh supported by armor and artillery. In addition ARVN Airborne and Rangers occupied a string of firebases along Rocket Ridge. On 23 April, the PAVN 66th Regiment in the 2nd Division formation, supported by the 37th Sapper Battalion and one T-54 company, started their attack on Tân Cảnh by hitting the ARVN tanks with wire-guided missiles and this was followed by a direct hit on the 42nd Regiment command bunker injuring the senior US adviser and several of the ARVN commanders and severely undermining the confidence of Col. Đạt. By midday all five of the M-41 tanks in the base and several more bunkers had been destroyed by the missiles. At 11:00 Vann landed to assess the situation and instructed the US advisers to prepare to escape and evade from the camp. At 19:00 PAVN rocket fire ignited the base ammunition dump
At 21:00 a column of 18 PAVN tanks was spotted in the area, an Air Force AC-130 gunship arrived at 23:00 and began to engage the T-54 tanks with its 105mm cannon. Three T-54s were disabled but later recovered by the PAVN. At midnight the tank column turned towards Tân Cảnh and the ARVN artillery began firing on the column until stopped by PAVN counterbattery fire. Two bridges on the approach to Tân Cảnh were abandoned without being destroyed. The ARVN organised hunter-killer teams and these destroyed two tanks.
Just before 06:00 on 24 April, the PAVN tanks attacked Tân Cảnh in two columns. One column of T-54s attacked the main gate, the other moving to secure the airstrip. The advance of the tanks caused the 900 support troops to panic. The new command bunker was hit by further artillery fire destroying the radio antennas. With the collapse of all command and control on the base, the American advisers abandoned the command bunker and moved to a new position to call in airstrikes, however fog made such airstrikes impossible. At dawn Vann arrived over Tân Cảnh in his OH-58A and made contact with the advisers who had escaped from the base perimeter. Vann landed and six advisers squeezed into the helicopter while frightened ARVN troops hung onto the skids. The helicopter flew to Đắk Tô II to drop off the passengers and then flew back to Tân Cảnh where they picked up the remaining three advisers, however the helicopter was swarmed by panicky ARVN and crashed on takeoff. Another helicopter came in and picked up Vann, his pilot and the three advisers and flew them to Pleiku.
One hour after the main PAVN attack on Tân Cảnh commenced, the PAVN began their attack on Đắk Tô II. A UH-1H helicopter #69-15715 landed to evacuate the six U.S. advisers who had been rescued from the Tân Cảnh perimeter, this helicopter was hit by PAVN anti-aircraft fire and crashed, five passengers and crew were killed in the crash while five survived, evaded capture and were recovered up 13 days later. The PAVN penetrated the base perimeter suffering heavy losses, the remaining U.S. advisers called in airstrikes as the morning fog cleared but by 10:00 the 47th Regiment commander had lost contact with most of his subordinates and the command group evacuated the command bunker for a bunker in the inner perimeter. A T-54 moved into the base and began direct fire on the command post, the two remaining M41s engaged the T-54, however their 76mm guns had no apparent effect on the T-54 which quickly knocked out both M41s. A relief column of M-41s supported by infantry arrived from Ben Het around this time, but all the M41s were knocked out by B-40 rockets and recoilless rifle fire and the infantry dispersed. With the failure of this counterattack and the loss of command and control the ARVN forces began to evacuate the base towards the south. As the ARVN attempted to cross the Dak Poko river they came under intense PAVN fire and the senior U.S. adviser Lieutenant colonel Robert Brownlee disappeared during this engagement. At 20:00 the 47th Regiment command group attempted to escape the base and by 04:30 on 25 April after losing several men to PAVN fire escaped the base perimeter and were recovered the following day. The attacking PAVN units at Đắk Tô II were the 1st Regiment (Ba Gia) of the 2nd Division formed the infantry assault along with the D10 Sapper Battalion, under the division commander Nguyễn Chơn. The supported T-54 tanks were from one battalion of the 203rd Tank Regiment.