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Artillery barrages from U.S. Army fire support bases proved devastatingly effective in both offensive and defensive roles.

EARLY IN THE MORNING a large Communist force was about to attack his small camp about 5 kilometers from the Cambodian frontier. Conrad, a West Point graduate commanding the 2nd Battalion, 8th Regiment, 1st Brigade, 1st Cavalry Division (Airmobile), had of April 1, 1970, Lt. Col. Michael J. Conrad knew to fight back with two understrength infantry companies, 80 artillerymen firing eight 105mm and 155mm howitzers and two 8-inch howitzers, and several immobile tanks. The Americans, 215 men in all, were hunkered down in a makeshift fort called Fire Support Base Illingworth, one of hundreds of firebases established—often temporarily—in enemy territory to protect and assist infantry troops on missions beyond the artillery range of the Army’s major bases.

At 2:17 a.m., after briefly barraging FSB Illingworth with mortars, rockets and recoilless rifles, 400 North Vietnamese Army soldiers of the 272nd Infantry Regiment broke from the jungle and swept toward the American position in wave attacks of about 40 men each. They were peppered by shot and shell from Illingworth’s cannons, machine guns and small arms but still managed to reach the American outworks where savage close combat ensued.

An hour into the battle, an enemy shell exploded a stockpile of 8-inch ammunition inside the base. The blast injured soldiers on both sides and stopped the NVA assault. Conrad, who later became a major general commanding the 1st Cavalry Division, and his men had survived an assault by a far larger force. By dawn on April 1, American reinforcements had secured the base. U.S. casualties totaled 25 killed and 58 seriously wounded—40 percent of the garrison. The NVA left 75 dead on the field and took an untold number of wounded and killed with them when they fled. The Americans abandoned Illingworth on April 2.

The combat at FSB Illingworth in 1970 shows how firebases, used by American forces in Vietnam since the mid-1960s as infantry support camps, evolved by the end of the war into an expanded mission: lure the North Vietnamese into attacking a relatively small force and then use the base’s strong firepower to inflict heavy losses on the attackers.

In late 1965, the U.S. Army had settled on a strategy for military operations in South Vietnam: American combat forces would be committed to offensive operations against the Viet Cong guerrillas and NVA regulars while supporting South Vietnam’s efforts to build up its internal defenses and undertake development projects. In the meantime, the Army of the Republic of Vietnam (ARVN) would deal with insurgency issues within its territory. To achieve the American goal, tactical “strike” and “consolidation” campaigns were employed. The strikes consisted of search-and-destroy missions, spoiling attacks, sweeps, raids and ambushes. The consolidation campaign was designed to eliminate the enemy in selected areas in order to secure key towns, facilities and roads. Fire support bases were fundamental components of both missions.

The fire support bases were capable of delivering overwhelming firepower using heavy-caliber artillery, not just mortars, recoilless rifles or small arms. In theory, each firebase formed part of an interlocking grid of artillery sites that would allow shells to rain down anywhere within the territory the U.S. Army wanted to control. Even on its own, the installation would be able to back up infantry patrolling within the area covered by its guns, since foot soldiers were never expected to operate without cannon support. Only on rare occasions did U.S. infantry or armor-maneuver elements operate beyond the range of friendly artillery.

The artillery at a fire support base usually included 105mm guns, which could hit an enemy more than 11,000 meters away, and 155mm guns with a range of 14,600 meters. Eight-inch howitzers (a range of 17,000 meters) and 175mm self-propelled guns (a staggering firing distance of 33,000 meters) might grace even the most isolated fire support base.

If two fire support bases were 22,000 meters apart with 105mm howitzers or 29,000 meters apart with 155mms, they could engage an enemy at any location between them with sustained high-volume fire, day or night. If 8-inch and 175mm pieces were thrown in the mix, fire support bases 66 kilometers apart could theoretically cover one another with shot and shell.

Regardless of the type of artillery placed inside them, fire support bases had tremendous combat power. A good example is FSB Crook, set up in April 1969 about 14 kilometers northwest of Tay Ninh, a city in Tay Ninh province. It housed troops from the 25th Infantry Division’s Company B, 3rd Battalion, 22nd Regiment, and A Battery, 7th Battalion, 11th Artillery Regiment. On call for support were the guns of several nearby fire support bases, as well as AH-1 Cobra gunships. FSB Crook’s mission was to help consolidation campaigns by interdicting NVA/VC infiltration and supply routes in the area.

On the nights of June 5-7, the Americans turned back ferocious enemy attacks. During the first assault, hundreds of NVA from the 271st and 272nd regiments hit the western side of the firebase as rocket and mortar fire slammed Crook. Pointblank fire from Battery A killed 76 of the surging NVA soldiers. After the initial fight, the battery commander, Captain Dick Neal, reported that “even at the height of the in-coming rounds, they [the American gunners] got out of their bunkers and fired their guns.”

The second night’s assault was a replay of the first night’s battle. This time the attackers included 430 men of the NVA 88th Regiment, who struck FSB Crook from the northeast and northwest. By the time the NVA broke off, 323 men had been killed and 10 captured. The U.S. casualty count was one dead and seven wounded. The base’s massive artillery power, accompanied by hefty support from Cobra helicopters and airstrikes from F-4 Phantoms, had done the job.

The U.S. military’s success at FSB Crook underscored the importance of mutual support among firebases, the use of artillery in both direct and indirect roles and the value of integrating helicopter gunships and artillery in simultaneous operations. It also showed that the defensive design of fire support bases was sound.

Firebase construction followed a pattern that was developed early in the war and became increasingly precise and effective. First, a thorough reconnaissance was made of the proposed site. The terrain had to fit the purpose of the firebase. The jungles and hills that covered large parts of South Vietnam posed serious problems for firebase designers. Was there a good field of fire around the perimeter, or would the jungle have to be cleared? Was it better to occupy a flat open field where helicopters could land or to seize mountain peaks where U.S. forces could command the surrounding countryside? Was the soil suitable for embedding the artillery? Was there a source of water on the site? Were civilians living in the area, or could it be considered a “free fire zone”? How fast could the site be fortified, and how long would it likely be used? How far away was logistic support, and on what scale could it be provided by land or by air?

An artillery commander wanted to make sure that guns at the site could support U.S. forces throughout the area of operations. He also wanted to have other artillery units close enough to help protect his base with indirect fire if necessary. An infantry commander looked for an easily defensible position, where artillery could be effectively coordinated with troop activity in any attack or defensive operations. The overall firebase operations were led by the camp’s senior officer, either an infantryman or an artilleryman, usually a captain or major.

Once a site was chosen, the building process would begin. First, a platoon-size security force and a combat engineer party of six to 10 men would arrive. Using demolition charges, hand tools and bulldozers when available, the engineers and infantry would construct bunkers, gunpits, earthen berms and wire barriers. Once the gun positions were ready, artillery units would prepare for firing, a process that took about five hours. In most instances, by nightfall on the first day infantry troops could dig in with overhead cover, typically structures made of corrugated sheet metal or wood with sandbags on top. On rivers and in swamps, where it wasn’t possible to build on the ground, firebases were established using floating gun platforms and pontoons.

Fire support bases were normally built to support a specific military operation and were used for three to 14 days. But firebases often became semipermanent because of the unit’s mission, the location’s importance or the difficulty of moving big weapons. FSB Mary Ann, used to disrupt NVA/VC supply lines, was built in February 1970 by the 23rd (Americal) Division in Quang Tin province, dismantled two months later and rebuilt in June. The base was still occupied well into 1971, even after the garrison suffered heavy losses when it was savagely attacked in March by the 409th VC Main Force Sapper Battalion.

Regardless of a firebase’s location or duration, its men felt isolated and anxious throughout their stay. It was “like being the cavalry hunkered down in a fort in the Old American West,” wrote Spc. 4 Fred Grant, a gunner with the 2nd Battalion, 77th U.S. Artillery Regiment, at FSB Gold, near the town of Suoi Tre in Tay Ninh province, in March 1967. “The difference was that the Indians, who seemed to always be surrounding the place, did not fight with bows and arrows;…[they] had AK-47s and RPGs and knew how to use them.”

Fire support bases were also used effectively in aggressive strike campaigns. They provided critical combat power for the 4th Infantry Division’s Operation Sam Houston, from January 1 through April 5, 1967, a mission to eliminate NVA/VC infiltration and troop concentrations in the western highlands of Pleiku province and to secure road networks there.

The enhanced firepower and protection of FSBs allowed the division to make 15 changes to its original objectives. For example, when enemy units infiltrated west of the Nam Sathay River, the division committed two infantry battalions to firebases in the area. The two battalions later made contact with North Vietnamese troops and with support from firebase artillery batteries engaged the enemy, inflicting heavy losses.

Intensive American artillery fire softened enemy positions, which diminished North Vietnam’s ability to attack and made its forces more vulnerable to counterstrikes by U.S. mobile combat units. Besides providing added firepower, the firebases contained supply, medical and maintenance facilities within easy distance of a division’s combat formations.

Fire support bases were important players in consolidation campaigns to secure key towns and roads. The 173rd Airborne Brigade’s action at FSB Floyd, in northern Binh Dinh province, typifies that kind of firebase support. Shortly before daylight on Aug. 29, 1970, the 3rd Battalion, 2nd NVA Regiment, was on its way to the Hoai An district to occupy base camps, replenish supplies and conduct operations against U.S. and South Vietnamese forces. American sensors and radar detected the movement, and FSB Floyd’s artillery units opened fire on the enemy along the route. A U.S. patrol that day discovered six dead and one wounded as a result of the American barrage. An NVA soldier hit by Floyd’s fire and captured one month later told his American interrogators that the artillery fire rendered his battalion combat-ineffective for several weeks.

By 1968 the American commanders in Vietnam felt that well-constructed, properly manned and supported firebases were practically invulnerable to attack. They then looked for other ways to use them and came up with the “anvil and hammer” concept: the anvil being the fire support base; the hammer, U.S. infantry and armor units. The bases delivered “offensive fire” to every part of the battle zone. Multiple bases fired simultaneously at enemy troops, attack-staging areas, weapons positions and command centers. The firebases then pounded enemy withdrawal routes and likely assembly areas. This system of deep, concurrent and continuous fire was employed at FSB Crook during its desperate fight in June 1969 and validated the concept.

The evolution of Vietnam fire support bases culminated in 1970, as exemplified in the 1st Cavalry Division’s operations. At the time, American and allied combat forces in South Vietnam were being drawn down (dropping to 350,000 in the early months of 1970 compared with more than 550,000 in 1969), and Washington decided to keep American casualties as low as possible by replacing combat maneuver with firepower. The 1st Cavalry’s leaders, looking for a way to best use their dwindling troop numbers against an enemy that seemed to be gaining strength each month, devised a response that emphasized speed, mobility and stealth.

Firebases were a key component of the plan, which worked this way: Company-size infantry units were sent to capture NVA supply caches and interdict supply routes. Once those targets were pinpointed, air and artillery were called in to destroy them. Instead of remaining stationary, artillery units were divided into batteries that moved around like infantry and armor units. Though the big guns had limited mobility, they could move enough to stay close to friendly units and keep the enemy guessing about their location. Additionally, roaming foot soldiers and armored vehicles rooted out enemy soldiers and exposed them to the artillery.

Under the new strategy developed to deal with the troop drawdown, firebases were smaller and thus seemingly more appealing targets for the enemy, but the bases could still hit back hard at the enemy they lured in because they were closely supported by infantry and many other firebases. The action at FSB Illingworth in April 1970 proved the overall soundness of the new role firebases played in the war’s waning years.

Throughout the conflict, fire support bases were a vital component of the U.S. war machine in Vietnam. They were instrumental in projecting American combat power in offensive and defensive operations. Firebases served as fortified staging points for sweeps into surrounding areas, places of refuge where U.S. forces could reorganize and refit and launching pads for artillery that protected the Americans. They also provided the most destructive force—sustained firepower—essential to the objective of all ground forces in war: annihilation of the enemy.


Arnold Blumberg, an attorney in Baltimore, served in the U.S. Army and writes for history publications on a variety of military topics.

Originally published in the August 2014 issue of Vietnam. To subscribe, click here.