During the early stages of the U.S. involvement in the Vietnam War, several U.S. Special Forces
Civilian Irregular Defense Group (CIDG) camps were established along the borders of South Vietnam in order to both maintain surveillance of PAVN and
National Front for the Liberation of South Vietnam (NLF or Viet Cong) infiltration and to provide support and training to isolated
Montagnard villagers, who bore the brunt of the fighting in the area. One of these camps was built near the village and airstrip at Đắk Tô. After 1965, Đắk Tô was also utilized as a Forward Operations Base by the highly classified
MACV-SOG, which launched reconnaissance teams from there to gather intelligence on the Ho Chi Minh Trail across the border in
Laos. In 1967, under the overall direction of commander of Special Forces in Vietnam Colonel Jonathan Ladd, the camp began to take mortar fire. Ladd flew in, organized reconnaissance and identified the entrenched hill bunker complex as the source of the shelling.
Đắk Tô lies on a flat valley floor, surrounded by waves of ridgelines that rise into peaks (some as high as 4,000 feet) that stretch westward and southwestward towards the tri-border region where South Vietnam, Laos, and
Cambodia meet. Western Kon Tum Province is covered by double and triple-canopy rainforests, and the only open areas were filled in by bamboo groves whose stalks sometimes reached eight inches in diameter. Landing Zones (LZs) large enough for helicopters were few and far between, which meant that most troop movements could only be carried out on foot. Temperatures in the highlands could reach 95° Fahrenheit (35° Celsius) during the day and could drop to as low as 55° Fahrenheit (12.78° Celsius) in the evenings.
In January 1967, Major-General (later LTG)
William R. Peers had taken command of the 4th Infantry Division, which had responsibility for the defense of western Kon Tum Province. Prior to the onset of the summer
monsoon, Peers set up blocking positions from the 4th Infantry Division's 1st Brigade base camp at Jackson Hole, west of
Pleiku, and launched
Operation Francis Marion on 17 May. The 4th had on hand its 1st and 2nd Brigades while its 3rd Brigade operated with the
25th Infantry Division northwest of
The II Corps Tactical Zone, the Central Highlands of South Vietnam
Throughout the middle of 1967, however, western Kon Tum Province became a magnet for several PAVN spoiling attacks and it appeared that the North Vietnamese were paying an increasing amount of attention to the area. Immediately after taking command, Peers instituted guidelines for his units in order to prevent them from being isolated and overrun in the rugged terrain, which also did much to negate the U.S. superiority in firepower. Battalions were to act as single units instead of breaking down into individual companies in order to search for their enemy. If rifle companies had to act independently, they were not to operate more than one kilometer or one hour's march from one another. If contact with the enemy was made, the unit was to be immediately reinforced.
 These measures went far in reducing the 4th Infantry's casualties.
These heavy enemy contacts prompted Peers to request reinforcement and, as a result, on 17 June, two battalions of Brigadier General
John R. Deane's 173rd Airborne Brigade were moved into the Đắk Tô area to begin sweeping the jungle-covered mountains in Operation Greeley. The 173rd had been operating near
Bien Hoa Air Base outside Saigon and had been in combat only against NLF guerrillas. Prior to its deployment to the highlands, Peer's operations officer, Colonel
William J. Livsey, attempted to warn the Airborne officers of the hazards of campaigning in the highlands. He also advised them that PAVN regulars were a much better equipped and motivated force than the NLF. These warnings, however, made little impression on the paratroopers, who were unaccustomed to PAVN tactics and strength in the area.
173rd Airborne troops during Operation Greeley
On 20 June, Charlie Company, 2nd battalion,
503rd Airborne Infantry (C/2/503) discovered the bodies of a Special Forces CIDG unit that had been missing for four days on Hill 1338, the dominant hill mass south of Dak To. Supported by Alpha Company, the Americans moved up the hill and set up for the night. At 06:58 the following morning, Alpha Company began moving alone up a ridge finger and triggered an ambush by the 6th Battalion of the 24th PAVN Regiment.
 Charlie Company was ordered to go to support, but heavy vegetation and difficult terrain made movement extremely difficult. Artillery support was rendered ineffective by the limited range of visibility and the "belt-grabbing" - or "hugging" - tactics of the North Vietnamese.
 Close air support was impossible for the same reasons. Alpha Company managed to survive repeated attacks throughout the day and night, but the cost was heavy. Of the 137 men that comprised the unit, 76 had been killed and another 23 wounded. A search of the battlefield revealed only 15 dead North Vietnamese.
U.S. headquarters press releases, made four days after the conclusion of what came to be called "
The Battle of the Slopes", claimed that 475 North Vietnamese had been killed while the 173rd's combat after action report claimed 513 enemy dead. The men of Alpha Company estimated that only 50–75 PAVN troops had been killed during the entire action.
 Such losses among American troops could not go unpunished. The operations officer of the 4th Infantry went so far as to recommend that General Deane be relieved of command. Such a drastic measure, however, would only provide more grist for what was becoming a public relations fiasco. In the end, the commander and junior officers of Charlie Company (whose only crime was that of caution) were transferred to other units.
and the Dak To area
In response to the destruction of Alpha Company,
MACV ordered additional forces into the area. On 23 June, the 1st Battalion, 1st Brigade,
1st Air Cavalry Division arrived to bolster the 173rd. The following day, the elite ARVN 1st Airborne Task Force (the 5th and 8th Battalions) and the 3rd Brigade of the 1st Air Cavalry Division arrived to conduct search and destroy operations north and northeast of
Kon Tum. General Deane sent his forces 20 kilometers west and southwest of Dak To in search of the 24th PAVN Regiment.
After establishing Fire Support Base 4 on Hill 664, approximately 11 kilometers southwest of Đắk Tô, the 4th Battalion, 503rd Airborne Infantry found the North Vietnamese K-101D Battalion of the Doc Lap Regiment on 10 July. As the four companies of the battalion neared the crest of Hill 830 they were struck by a wall of small arms and machine gun fire and blasted by
B-40 rocket-propelled grenades and mortar fire. Any advance was impossible, so the paratroopers remained in place for the night. The following morning, the North Vietnamese were gone. The 4th of the 503rd suffered 22 dead and 62 wounded. The bodies of three PAVN soldiers were found on the site.
North Vietnamese pressure against CIDG outposts at
Dak Seang and
Dak Sek, 20 and 45 kilometers north of Đắk Tô respectively, was the impetus for dispatching the 42nd ARVN Infantry Regiment into the area while the ARVN Airborne battalion moved to Dak Seang. On 4 August, the 1st of the 42nd encountered the North Vietnamese on a hilltop west of Dak Seang, setting off a three-day battle that drew in the South Vietnamese paratroopers. The 8th Airborne, along with U.S. Army advisers, was airlifted into a small unimproved air field next to the Special Forces camp at Dak Seang. The camp was under sporadic fire and probing ground attack by PAVN forces. This occurred when its Special Forces commander and a patrol failed to return and the camp received what appeared to be preparatory fire for a full scale ground attack by PAVN. The terrain was high mountains with triple canopy jungle. The importance of the Dak Seang camp was that it lay astride the Ho Chi Minh Trail, the main infiltration route of the PAVN into the South.
About a kilometer from the camp, the Army advisers and the 8th Airborne came upon the bodies of the lost Special Forces patrol, all dead, including the camp commander. As the 8th Airborne moved up the mountain, the lead elements were taking small arms fire. Before long, it was obvious that the PAVN troops had filtered down on all sides. By noon of 4 August, the 8th Airborne with its advisers were in a fight that lasted several days. When the unit finally overwhelmed the PAVN forces because of superior firepower in air and artillery, it reached the top of the mountain and found a fully operational PAVN Headquarters, complete with hospital facilities and anti-aircraft emplacements. During the three-day battle, the 8th Airborne Battalion alone withstood six separate ground attacks and casualties among all the South Vietnamese units were heavy.
By mid-August, contact with communist forces decreased, leading the Americans to conclude that the North Vietnamese had withdrawn across the border. The bulk of the ARVN Airborne units were then returned to their bases around Saigon for rest and refitting. On 23 August, General Deane turned over command of the 173rd to Brigadier General Leo H. Schweiter. On 17 September, two battalions of the 173rd departed the area to protect the rice harvest in Phu Yen Province. The 2nd of the 503rd remained at Đắk Tô along with the 3rd ARVN Airborne Battalion to carry out a sweep of the Toumarong Valley north of Đắk Tô and the suspected location of a PAVN regimental headquarters. After three weeks of fruitless searching, however, the operation was halted on 11 October. Operation Greeley was over.