Battle of FSB Mary Ann

Battle of FSB Mary Ann
Part of the Vietnam War
Date March 28, 1971 Location 15°18′20″N 108°6′37″E / 15.30556°N 108.11028°E / 15.30556; 108.11028 (FSB Mary Ann)Coordinates: 15°18′20″N 108°6′37″E / 15.30556°N 108.11028°E / 15.30556; 108.11028 (FSB Mary Ann) Quang Tin province, South Vietnam MGRS AS 962-998[1] Result Viet Cong victory
Belligerents
United States	Viet Cong
Commanders and leaders
William P. Doyle	Unknown
Units involved
23rd Infantry Division "Americal" 1st Battalion, 46th Infantry Regiment 2nd ARVN Division Battery B, 22nd Field Artillery	Military Region 5 409th VC Main Force Sapper Battalion[2]
Strength
231 U.S. 21 ARVN	~50
Casualties and losses
33 KIA, 83 wounded	15 found dead

The Battle of FSB Mary Ann occurred when Viet Cong sappers attacked the U.S. firebase located in Quang Tin province, South Vietnam early on the morning of 28 March 1971.

Fire support base (FSB) Mary Ann was located to interdict movement of enemy troops and materiel down the K-7 Corridor and Dak Rose Trail (branches of the Ho Chi Minh Trail running from Laos to the coast of South Vietnam). Originally intended to be a temporary base, it evolved into a more permanent location garrisoned by at least one company of U.S. ground forces. The base was manned by 231 American soldiers at the time of the attack.^[3]

The firebase was scheduled to be handed over to the South Vietnamese Army when the 1st Battalion, 46th Infantry Regiment (1-46th Inf) moved to the north. 21 Army of the Republic of Vietnam (ARVN) soldiers from Battery B, 22nd Field Artillery, along with their two 105mm howitzers, were on Mary Ann to support ARVN operations to the south.^[4]

For months leading up to the attack the level of enemy activity in the area had been low and contacts were infrequent. The lack of significant recent engagements, along with preparations to turn the FSB over to AVRN units, had given the U.S. soldiers in the area a false sense of security. The sapper attack was sharp and very successful, with repercussions up the 23rd Infantry Division's (23rd ID) chain of command.

Background and Base Construction

FSB Mary Ann was initially established on 19 February 1970 by elements of the 1st Battalion, 46th Infantry (part of the 196th Light Infantry Brigade (196th LIB)). At the time it was not intended to be a permanent base, and was closed by the same Battalion about two months after it was opened.^[5] Operational needs brought the 1-46th Inf back to Mary Ann on 27 June, and the base was put back into operation. According to one Battalion commander it was a poor location for a firebase from a defensive standpoint. "[The FSB was built] in a saddle with hills around it on three sides." It was also at the very edge of helicopter range from Americal headquarters at Chu Lai. Any other location in the region would have put the FSB outside the range of the Division's heavy artillery batteries and prevented artillery at Mary Ann from shelling key locations in the region. From an offensive standpoint the FSB was in a good location since it straddled the Dak Rose Trail network.^[6]

FSB Mary Ann's construction was no different from many other U.S. firebases in South Vietnam. Running northwest to southeast, the firebase stretched 500 meters along the crest of a 200 meter high ridge connecting two hillsides. Only 75 meters wide at its narrowest point, Mary Ann widened to 125 meters at the northwest and southeast ends. A trench, "knee-deep in certain stretches and waist-deep in others" defined the base's perimeter and connected the base's twenty-two bunkers. Like any typical late-war FSB, most of Mary Ann's bunkers were made from converted metal shipping containers known as conexes. In addition to the conex bunkers, Mary Ann had over thirty assorted structures (hootches, sandbagged bunkers, and other makeshift structures). The southeast end of FSB Mary Ann housed the Battalion Tactical Operations Center (B-TOC) and Company Command Post (CP), both located next to a small VIP helipad. The base's mess halls, a communication center, the Battalion aid station, ammunition bunkers, storage for general supplies, and two artillery firing positions were also located at this end of the FSB. The northwest end of the base housed a second artillery position with two 155mm howitzers, the fire direction center and the artillery command post. The saddle between the two ends of the FSB served as the resupply helipad. Dirt roads divided both ends of the base, and also ran outside the wire at two points: southwest past a firing range to the spring that served as the base's water point and northwest to the trash dump.^[7]

Soon after being reopened, FSB Mary Ann was probed many times (four attempts are recorded between July and August of 1970) and one author states that the base could have been easily observed from the high ground surrounding its location. The last major contact in the area was a firefight on 13 August, when Company A, 1-46th Infantry hit and overran "what was probably the NVA command post for the area." After that firefight, organized resistance seemed to cease. That quiet, combined with the usual cycle of replacements at all levels of American units (from individual riflemen to the Company and Battalion commanders), led to what the outgoing Battalion commander called an "awfully complacent" mindset.^[8]

At the time of the attack, FSB Mary Ann was garrisoned by Charlie Company, 1-46th Infantry (75 men commanded by Capt Richard V. Knight). In addition, 18 men from Echo Company's Reconnaissance Platoon were at the base preparing for an operation the following day. These troops shared space with 34 support personnel (medics, radiomen, etc.) from 1-46th's Headquarters Company (HHC). The rest of the garrison (less the ARVN artillerymen) came from elements of Alpha, Bravo, and Delta companies, 1-46th (22 men who were in transit between their units and areas further to the rear), and assorted artillery personnel (including the crew of a quad-.50 caliber machine gun from Battery G, 55th Field Artillery). According to one source all ground surveillance radars and night vision (starlite) scopes formerly at Mary Ann were "sent to the Battalion rear for maintenance." This left the base with a series of ground sensors designed to detect movement located "within fifteen hundred to forty-eight hundred meters" of the perimeter. These sensors had been picking up movement since shortly after the base was reopened, but no contact had ever resulted from the readings.^[9]

Charlie Company was the only complete company at Mary Ann due to operations south and east of the FSB near a location called Landing Zone (LZ) Mildred. Companies A and B, 1-46th Inf, were on the ground in that area of operations, and some of the artillery previously located at Mary Ann had been moved to LZ Mildred to support operations there (including the 81mm mortars assigned to both companies and the heavy 4.2-inch mortars normally part of Company E). Prior to the attack, the attention of the Battalion commander (LtCol Doyle) was focused more on operations near LZ Mildred. In fact, the Battalion command post was scheduled to move there on 28 March. This impending move led to a freeze on all new construction at Mary Ann, including fencing to block the roads leading out of the FSB.^[10]

Battle

Early accounts of the attack state that the defenders "failed to safeguard the perimeter" of the FSB.^[11] The only single volume study written about the attack contests this position, pointing out that "historians [including the author of the book, who had discussed Mary Ann in an earlier work] got it wrong."^[12] Even with this new perspective, there are indications that alertness at Mary Ann was not as good as it could have been. Many accounts by men stationed at Mary Ann mention that perimeter security was uneven at best. One member of the 1-46th Headquarters Company stated that "I don't think Captain Knight [the commander of Charlie Company, 1-46th Inf] had a clue as to how lax the security was...because in that area, and only that area, Knight wasn't diligent. He left it up to his lieutenants and sergeants to check the bunker line." In many cases they failed to do so, and the failure was compounded by Charlie Company being understrength and unable to man all the perimeter bunkers.^[13] Manning bunkers was not the only problem. Trip flares located in the concertina wire around the base were not always reset or replaced when they went off, a common occurrence caused in some cases by the rotor wash created by large CH-47 Chinook helicopters bringing in supplies or backhauling material as 1-46th Inf prepared to hand the base over to the ARVN.^[14] This lax attitude, combined with the skill of the attacking sappers, had fatal consequences for many in Charlie Company. Although not "cringing in their bunkers",^[15] the defenders of Mary Ann were not prepared for a ground attack. This lack of readiness was not noted by the 196th LIB commander, Colonel William S. Hathaway, who visited the base on 27 March, the day before the attack. He later stated that what he'd seen at Mary Ann that day "was a big improvement over that I had seen before...the troops were alert."^[16] These accounts failed to mention the skill of the sapper unit launching the attack and focused instead on the American unit defending the base, creating an incomplete picture of the attack.

On the night of 28 March sappers from the Viet Cong (VC) 409th Sapper Battalion approached the wire of FSB Mary Ann and took up positions to launch an attack. The exact number of sappers involved is uncertain, but most sources agree that there were at least 50. As was common practice for such units, the sappers wore khaki shorts and soot camouflage and were armed with either an AK-47 or RPG-7 and satchel charges and grenades to attack bunkers. Sappers relied on stealth, shock and surprise to give them an advantage, and rarely carried heavy weapons or equipment. The 409th was known to the intelligence section of the 196th LIB, but had previously operated against ARVN targets north of Quang Tin Province. It was assumed by the 196th LIB's intelligence personnel that both the 409th and the 402nd Sapper Battalions were operating to the east of FSB Mary Ann, preparing to attack ARVN targets in that region. None of them predicted an attack on the US base.^[17]

The ground attack targeted the south side of FSB where the ground gently sloped away from the perimeter. The northeast side was marked by a steep slope toward a river, not conducive terrain for a sapper attack. The sappers moved in small squads of three to six men, cutting four paths through the base's two outer concertina barriers. They took more time moving through the third barrier, which was about 20 meters from the bunker line, and then fanned out along the southwest side of the line. Following standard sapper doctrine, they would attack as soon as the mortar barrage commenced.^[18] The first 82mm mortar shells hit FSB Mary Ann at 2:30 AM, signaling the start of the ground attack.^[19]

The surprise attack by the VC had the effect of immobilizing the camp's defenders, but those who survived the initial onslaught managed to mount resistance against their attackers. During the ensuing fire-fight, some of the enemy gunfire seemed to come from the ARVN section of the camp, while ARVN soldiers were nowhere to be seen. However, one US soldier who was wounded and remained in the ARVN sector for the duration of the fight has stated that he never saw any ARVN firing toward US positions.^[20] The ARVN battery was located in the northern sector of the FSB, which was not attacked by the sappers. The Tactical Operations Center (TOC) was struck by 82mm mortar shells, which awakened and subsequently incapacitated Lt. Col. William P. Doyle.

Once Lt. Col. Doyle had regained consciousness, a request was made for helicopter gunships and illumination. At that point, the south end of the Tactical Operations Center was burning, after a sapper had set off a satchel charge that caused a case of white phosphorus grenades to ignite. Despite suffering from severe wounds, Doyle made his way out of the TOC and started firing his M-16 at the sappers, but he was knocked out again by a grenade.

At 02:51, radio telephone operator David Tarnay managed to raise LZ Mildred, when Lieutenant Thomas Schmitz requested artillery positions to adjust their guns and fire at Fire Support Base Mary Ann to save the surviving Americans there. Doyle then informed Schmitz that the TOC would be evacuated and they would lose radio contact.

Doyle and another officer had moved to the south end of the firebase at 03:20 when another group of VC sappers appeared and started up the hill. At around 03:30, the VC disengaged and withdrew from the firebase dragging their dead and wounded comrades through the wires of the firebase, when a helicopter gunship arrived and began firing its guns at the sappers. The wounded survivors of the 1st Battalion were finally airlifted out when Lt. Col. Richard Martin, commander of the 3rd Battalion, arrived with the medevacs.

On the next day at 16:00, the NVA or Viet Cong swept FSB Mary Ann with machine gun fire with one U.S. soldier wounded as a result.

Controversy and Aftermath

Prior to the attack on FSB Mary Ann, there had been reports of possible Viet Cong infiltration within the ranks of the ARVN contingent present on Mary Ann. In one incident, a man wearing the insignia of an ARVN lieutenant inquired about the easiest way to get off the firebase because his men wanted to go fishing. He was told the easiest way in and out of the camp was the south end of the firebase. As mentioned above, the ARVN side of the perimeter was not attacked, but the 23rd ID's Inspector General (IG) team noted that the northeastern side of the base was "generally untouched, including the Battalion ammunition storage area. The actions of ARVN soldiers were no different from many US soldiers in taking cover until the attack was over."^[21] The ARVN decided not to garrison the firebase after the attack and it was closed on April 24, 1971.

The battle for FSB Mary Ann inflicted serious losses on the defenders, who suffered 33 killed and 83 wounded. Overall VC casualties remain uncertain, but 15 bodies were located in the aftermath of the attack. Blood trails and drag marks indicated that the Viet Cong may have suffered more casualties, but the extent of those losses were never verified.^[22]

Both the attack and events that followed (including a report that VC bodies were burned in the aftermath) led to an investigation by the 23rd ID's IG and a separate investigation by the IG at MACV level. While the 23rd ID's IG report limited its findings to suggestions that "[a] Strong command emphasis be placed on upgrading fire base security procedures and improving defensive measures against sapper attacks", the MACV IG findings were much more serious, tracing the failures all the way up to Division command level.^[23]

Events at FSB Mary Ann had repercussions throughout the chain of command of both the 23rd ID and the 196th LIB. In July 1971, Maj. Gen. James L. Baldwin was replaced as commander of the 23rd ID, with military sources quoted in news reports suggesting he was relieved because of the attack on FSB Mary Ann.^[24] Other sources indicate that Baldwin was technically "reassigned" and not relieved of command (which is a more serious, official action). In spite of recommendations by the deputy MACV IG that he be reduced in rank and given a letter of reprimand, Baldwin received a letter of admonishment for events at FSB Mary Ann and retired as a major general in 1972.^[25] Colonel William S. Hathaway, commander of the 196th LIB, was removed from the promotion list for Brigadier General, and Lieutenant Colonel William P. Doyle was reprimanded.^[26] Doyle remained in service until his retirement but did not receive another promotion. In the end, six officers (including Major General Baldwin and the assistant division commander) received some sort of disciplinary action from the Secretary of the Army.^[27]

FSB Mary Ann and History of the Vietnam War

The fight at FSB Mary Ann has been used by historians to illustrate the decline of American military units in Vietnam. Historians taking this position include Shelby Stanton^[28] and Lewis Sorley, giving the action high prominence in accounts of the U.S. Army's last years in Vietnam. Sorley's account is particularly harsh, stating that the 1-46th Inf "was riddled by drugs and incompetence" and that "[t]he disaster was compounded by a cover-up that extended all the way up to the Division commander."^[29] Keith Nolan initially had a similar opinion, but later changed his mind after researching the action and writing his definitive account Sappers in the Wire.

Sorley's account further states that FSB Mary Ann was somehow unique. "Had there been other units as careless and undisciplined as the one at Mary Ann, surely the enemy would have discovered and exploited their weaknesses just as ruthlessly. Yet that did not happen."^[30] However, there were other serious attacks mounted by VC and NVA units against fire support bases during the Vietnam War, many against units that had better combat reputations than the Americal/23rd Infantry Division.

Notes

References

• Fulghum, David (1984). The Vietnam Experience: South Vietnam on Trial (Mid-1970 to 1972). Boston Publishing Company. 
• Kelley, Michael P. (2002). Where We Were In Vietnam. Hellgate Press. ISBN 1-55571-625-3. 
• Nolan, Keith William (1995). Sappers in the Wire: The life and death of Firebase Mary Ann. Texas A&M University Press. ISBN 0-89096-657-5. 
• Sorley, Lewis (1999). A Better War: The Unexamined Victories and Final Tragedy of America's Last Years in Vietnam. Harcourt. 
• Stanton, Shelby L. (1985). The Rise and Fall of an American Army. Presidio Press. 

External links

• Deadly Sapper Attack on Fire Support Base Mary Ann During the Vietnam War
• 174th Assault Helicopter Company - links to picture of FSB Mary Ann