On 18 June 1971, the biggest engagement between Allied and Communist forces in Phu Yen Province since 1968 transpired in Son Hoa District. During the 1968 Tet Offensive, Communist forces made three failed attempts to capture the province capital of Tuy Hoa City. Three years later, the sounds of impacting mortar rounds and B-40 rockets marked the start of t the People’s Liberation Armed Forces (PLAF) attempt at overrunning the Government of Vietnam (GVN) assets at Cung Son.[1] Accomplishing such a feat would effectively evict the GVN from Song Hoa District, thus giving the National Liberation Front (NLF) full control of western Phu Yen. To reach the GVN facilities, enemy forces descended on an area to the northwest of the district. Roughly two kilometers to the northwest to the Song Hoa District Headquarters, sat Hon Ngang, a hill which dominated the terrain around Cung Son. Atop the hill stood Regional Force (RF) Group 53’s headquarters and firebase.

The Battle of Cung Son began at 0230, with a PLAF mortar barrage. By 0300, the PLAF launched a two-pronged ground assault, targeting the Son Hoa District Headquarters and airstrip as well as the nearby RF Group 53 Headquarters and firebase atop Hon Ngang. PLAF sappers attacked the airstrip and assailed Hon Ngang with small arms, engaging two RF companies defending the RF Headquarters. Meanwhile, the K-13 Local Force Battalion entered Song Long hamlet to prevent the South Vietnamese from reinforcing the district headquarters. The 96th Local Force Battalion moved on Son Ha hamlet as to thwart possible South Vietnamese attempts at relieving Hon Ngang from the southwest.[2]    

Captain Ronald Thayer, the CORDS Advisory Team 28’s District Senior Advisor (DSA) in Son Hoa, had been on the job for just a few hours. Thayer’s experience as an artillery officer during two previous tours payed dividends. He helped direct precise mortar fire, breaking up the enemy attack against the GVN assets.[3] His counterpart, South Vietnamese District Chief, Major Nguyen Phu Hieu, proved himself a capable commander, directing his territorial forces to outflank the enemy. While the ardent RF defenders slowed the PLAF advance, the enemy nonetheless retained the advantage. Upon realizing the precariousness of the situation, Hieu radioed for immediate assistance. Hieu had much at stake; a North Vietnamese by birth fighting for Saigon almost assuredly meant his demise should he fall into PLAF hands.[4] Assistance materialized in the form of Huey gunships of the 134th Aviation Company. These gunships provided much needed fire support in and around RF 53 Headquarters. Other helicopters, or “Devils,” eventually ferried in reinforcements.[5]

The PLAF’s assault continued unabated through 0600, with RF units continuing to engage the enemy on Hon Ngang. Here, RF artillery fired at zero elevation, which “greatly deterred the enemy access to the artillery positions.”[6] “Although close to being overran during the engagement,” read the U.S. after action report, RF artillery crews “met the enemy face on and used their artillery pieces in the most outstanding defensive role.”[7] The South Vietnamese artillery disrupted PLAF attempts to quickly secure the firebase for itself. The arrival of additional gunships did not prevent the enemy from dislodging two RF platoons from south of the Song Ba to south of the RF Headquarters. Other RF troops moved to reinforce the RF Headquarters, establishing positions on the overlooking the hill to the east. For reconnaissance purposes, two RF platoons moved to the western extremity of Son Long village, while another RF recon element ventured to Son Hoa village. At 0730, Province Senior Advisor Russell L. Meerdink and the GVN’s Deputy for Security landed at the District compound via helicopter. With substantial enemy movement to the north of the RF Headquarters, Hieu and Thayer began requesting airstrikes, striking the enemy just north of Hon Ngang. Two days after the battle, 31 PLAF bodies would be found in the vicinity of that airstrike.[8] The presence of such a number of enemy dead was testament to the ferocity of fight for the RF Headquarters.

The arrival of RF Mobile Battalion 206 turned the tide of the battle. The insertion of RF Mobile Battalion 206 occurred between 0900 and 0930 hours to the north of Son Ha village. Concurrently, American gunships received incoming enemy rounds from Son Long village, responding with machine-gun and rocket fire. Thirty minutes later, two of RF Mobile Battalion 206’s companies engaged the enemy on Hon Ngang[9]. The actions of these two companies shattered the enemy attack and placed the hill firmly under RF control. The fight on Hon Ngang claimed the lives of 28 PLAF and 14 RF troopers. With its attack stymied, the remnants of PLAF’s 96th and K-13 local force battalions took cover in the buildings of nearby villages.[10]

South Vietnamese forces then moved to encircle the villages, as American gunships circled overhead. At 1000, four Popular Force (PF) platoons established blocking positions along the southeastern border of Son Long village. Helicopters inserted one company of RF Mobile Battalion 206, which moved to the village’s northwestern extremity and awaited reinforcements. Between 1030 and 1100, the remaining elements of the reaction force arrived and assumed positions to the left of the first company. By noon, South Vietnamese forces encircled the K-13 Local Force Battalion’s positions within Son Long, and Hieu and Thayer requested a PSYOP mission to encourage the village inhabitants to evacuate. Surprisingly, the enemy permitted the inhabitants to leave, knowing full well that the absence of non-combatants would ensure airstrikes.[11]

Before the airstrikes commenced, gunships engaged enemy targets in Son Long. Concurrently, a company of the RF Mobile Battalion 206 attempted entry into the village, but fell back in the face of intense enemy fire. Another company of the RF Mobile Battalion 206 moved further west in order to attack the village from that direction. Nevertheless, repeated RF assaults that afternoon could not break through the enemy’s wall of fire. Gunships, too, failed to dislodge the enemy from the village’s buildings. Yet the gunships fought on and an RF company made one last effort to enter the village; this time from the north. These attacks also proved unsuccessful, thus by 1630, the Forward Air Controller requested an airstrike. At 1715, an airstrike rocked the village, driving some PLAF to break-off contact by moving northward where they quickly encountered fire from RF soldiers. By 2000 hours, the battle reached its apogee as an RF unit entered Son Long and engaged the remaining PLAF in a series of firefights. Nightfall ended the intense exchange, with fire resuming, and the battle ending, the next morning.[12] Province Chief Lt. Col. Nguyen Van To surmised that the RF won the day partially because the enemy had nothing but contempt for their South Vietnamese foes, suggesting the Communists had not anticipated being outflanked by Saigon’s forces.[13] Ultimately, between 127 and 187 PLAF perished in the battle of Cung Son.[14] The attack against GVN assets in Cung Son “virtually annihilated” the K-13 Local Force Battalion.[15]

The Battle of Cung Son demonstrated the importance of U.S. air cover for South Vietnamese units and decisive leadership during the Vietnamization period. The American helicopters ferried in RF Mobile Battalion 206, the troops necessary to eject the PLAF from Cung Son. Moreover, the helicopters provided much needed fire support, a key advantage considering the nearby artillery was preoccupied with PLAF sappers. Both Thayer and Hieu directed the assets at their disposal to counter a determined PLAF assault. For his role, Thayer received the U.S. Army’ Bronze Star, with the ARVN bestowing him with a Cross of Gallantry with Gold Star.[16] With the withdrawal of substantial American ground forces, the South Vietnamese assumed an increasingly heavier burden of fighting the war. The aggressive spirit on part of the RF and local GVN leadership pleased the American advisors.[17] The firepower wrought by the 134th Aviation Company proved indispensable, with the deft maneuvering of the RF providing the coup de gras. Without such air support, the battle could have gone quite badly for Thayer and Hieu. Events at Cung Son unveiled a truth about the war in Phu Yen and the Vietnam War in general; the South Vietnamese could defeat a sizable PAVN and PLAF force, but only with the support of U.S. airpower.

Yet the victory at Cung Son came at a high price. Indeed, the battle resulted in “the destruction of 228 homes, many cattle and hogs and the deaths of 8 civilians. Nine hundred seventy people were made homeless.”[18] For locals, the battle demonstrated that, despite years of fighting, the end of the war remained out of sight. While supplies were quickly flown in, such devastation meant restarting, not advancing pacification. Higher echelons of CORDS reported that, “although a victory for the GVN,” the battle of Cung Son “demonstrates some similarity to the Phu Nhon battle in Pleiku in March in that there was occupation of hamlets from which the war was waged with the inevitable result of a set back in the pacification program for the district.[19]” Thus for Phu Yen as a whole, bloodying the enemy at Cung Son occurred at the cost of advancing pacification. Instead of focusing resources on intensifying the Saigon government’s control in Son Hoa District, efforts were directed towards rebuilding the hamlets and the people’s trust in the GVN to protect them. For the aforementioned reasons, what transpired at Cung Son functions as lesson that battlefield triumphs do not always equate to winning a war.

Robert J. Thompson is a PhD Candidate in US History at the University of Southern Mississippi. He recently completed his dissertation "More Sieve Than Shield: the U.S. Army and CORDS in the Pacification of Phu Yen Province, Republic of Vietnam, 1965-1972."

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Header Image: The hamlet of Cung Son the morning after the battle. (Hans-Jürgen Underwood)

Notes:

[1] GVN Son Hoa After Action Report, 18 June 1971, p.1, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, McCain Library and Archives (MLA); “Author’s Notes on Son Hoa A/A Rpt,” Undated, p.1, Folder 25, Box 2, Courtney L. Frobenius Papers, M396, McCain Library and Archives (MLA); Military Region 2, Military Region Overview, Period Ending 30 June 1971, p.2, Historian Files, U.S. Army Center of Military History (CMH); Ronald Thayer interview; “Author’s Notes on Son Hoa A/A Rpt,” Undated, p.1, Folder 25, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[2]  GVN Son Hoa After Action Report, 18 June 1971, p.1, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[3] “Award of the Bronze Star,” 29 December 1971, in the author’s possession.

[4] Ronald Thayer. Interview by author. Telephone interview. 15 December 2015

[5] GVN Son Hoa After Action Report, 18 June 1971, p.2, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[6] Ibid., 1.

[7] Ibid.

[8] Ibid., 2.

[9] GVN Son Hoa After Action Report, 18 June 1971, p.2, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[10] “Author’s Notes on Son Hoa A/A Rpt,” Undated, p.2, Folder 25, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[11] Thayer interview.

[12] GVN Son Hoa After Action Report, 18 June 1971, p.3, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[13] “Author’s Notes on Son Hoa A/A Rpt,” Undated, p.2, Folder 25, Box 2, Courtney L. Frobenius Papers, M396, MLA.

[14] GVN Son Hoa After Action Report, 18 June 1971, p.3, Folder 24, Box 2, Courtney L. Frobenius Papers, M396, MLA.; “Author’s Notes on Son Hoa A/A Rpt,” Undated, p.2, Folder 25, Box 2, Courtney L. Frobenius Papers M396, MLA. Note: The American and South Vietnamese AARs differ on the number of PLAF killed. The Americans placed the enemy KIAs at 127, while the South Vietnamese put the number at 186.

[15] Military Region 2, Military Region Overview, Period Ending 30 June 1971, p.3, Historian Files, CMH.

[16]  “Award of the Bronze Star,” 27 December 1971, in Ronald Thayer’s possession.; RVN Cross of Gallantry with Gold Star, 16 July 1971, in Ronald Thayer’s possession.

[17] Advisory Team 28, Province Report, Period Ending 30 June 1971, p.2, Historian Files, CMH.

[18] Ibid., 4.

[19] Military Region 2, Military Region Overview, Period Ending 30 June 1971, p.1, Historian Files, CMH.