Launched on 26 July 1971 against the Ho Chi Minh Trail complex and its People's Army of Vietnam (PAVN) garrison, Sayasila was planned as a rather complex two phase operation dependent on coordinating two columns containing 4,400 troops with close air support in an attack on 1,100 Vietnamese Communist soldiers.

When the assault stalled in mid-August, it was elaborated upon with two additional helilifts of Royalist troops behind the PAVN's mobile garrison.

Bolstered by a fresh regiment of guerrillas as reinforcements, plus support by a minimum of 40 daily U.S. Air Force strike sorties, the Operation Sayasila offensive was renewed on 10 September 1971.

Its importance can be measured by the fact that among the many attempts to cut the Trail, the multi-divisional Operation Lam Son 719 was launched on 8 February 1971 to capture Tchepone.

Military Region 4's (MR 4) Commanding Officer General Phasouk Somly was hesitant to try another attack because of the poor fighting qualities of his troops.

[3] Thus it was that Pakse Unit of the Central Intelligence Agency (CIA) planned an offensive into communist territory on the eastern Bolovens Plateau designed to block one of the supply arteries of the Ho Chi Minh Trail, Route 23.

In phase one, MR 3's guerrillas would be airlifted to capture the Pakse 47 airfield southwest of Salavan at UTM coordinates XC5237.

Phase two would be a squeeze play; a mobile force would be airlifted to a position northwest of Paksong, while a column probed eastward toward it along Route 23.

Three days before the operation's scheduled start, they requested and received a commitment for 12 daily sorties of tactical air for the next month.

The U.S. Air Force (USAF) would fly interdiction strikes on the communist lines of communication with fighter-bombers by day and gunships by night.

General Minh, commander of the PAVN battalions, would use this flaw to defeat the Royalists in detail by using his interior lines of communication.

[7] On 26 July 1971, MR 3's Groupement Mobile 31 (GM 31) stood down from a planned heliborne insertion into Salavan in Military Region 4.

After vigorous protests from the CIA concerning the humiliation of failing to fulfill the King's and the Prime Minister's wishes, the helilift was re-approved.

The plea that diversionary operations were already being launched, and that failure to follow through would prejudice Lao military efforts against the Ho Chi Minh Trail carried the day.

Tactical air cover found no worthwhile targets as the irregular regiment occupied a town vacated by the People's Army of Vietnam (PAVN) by 08:30.

At 09:20 hours on 29 July, Bataillon Volontaires 41 (BV 41) was helilifted out of Pakse and deposited 34 kilometers northeastward to the Bolovens Plateau.

After a patch of ill weather delays in flight operations, Bataillon Infanterie 4 (BI 4) joined them, bringing the Royalist roster to 1,250 troops available.

Two battalions each of Thai mercenaries, Royalist regulars, and Neutralists were helicoptered to a landing zone south of Paksong, with orders to capture it.

Instrument flight rules target boxes containing no friendly forces were delineated so radar-directed bombing in them could occur despite unfavorable weather.

They also managed to persuade neighboring MR 3 to loan them another guerrilla regiment, Groupement Mobile 32 (GM 32) to continue the assault.

By the next morning GM 32 had secured a position on the Phou Theveda high ground athwart Route 232, four kilometers east of Paksong.

The following day, 12 September, a levy of 670 reinforcements cobbled together from three different commands were flown into a landing zone seven kilometers southeast of Paksong.

Political pressure from Vientiane was being brought to bear on the operation's commanding officer, as the Royal Lao Armed Forces had suffered almost 1,000 casualties in the past two months in MR 4.

[19] On 11 September, the Thai mercenary artillery battery opened fire from Ban Gnik, immobilizing the Communists further east on Route 23 with a barrage of 500 shells.

This freed GM 31 to advance 20 kilometers west along Route 16 before moving south to capture Lao Ngam on 2 September.

[20] On 26 October, a Thai mercenary battalion swept south and east of Paksong, reoccupying the Phou Thevada high ground.

[24] The directive, issued by the Joint Chiefs of Staff and agreed to by both the CIA and the State Department, required coordination of planned operations with both 7th Air Force and CINCPAC.

The Communists still controlled the eastern Bolovens Plateau as a territorial shield protecting the Ho Chi Minh Trail.