In order to permit the most effective use of helicopters, the engineering units had to ensure that the ground approach to, and exits from, the landing zone were at least as wide as two rotor blade diameters. Those approaches had to remain clear of communications wire and all other obstacles. There also had to be an area clear of obstructions 30 feet or higher extending at least 150 feet in the direction of the approach and exit paths, giving loaded helicopters an opportunity to gain forward velocity before they had to commence climbing.
A typical FSB provided an area large enough for a battery of artillery (usually a mixed battery of 105mm and 155mm howitzers and 4.2-inch mortars), an infantry battalion command post, a logistics support area, and an aid station. This required a clearing of substantial size for the landing of helicopters and implementation of artillery pieces, ammunition berms and personnel.
As soon as the initial landing zone was established, additional equipment and demolitions were airlifted in to facilitate the development of the gun pits and ammunition berms. The placement of the artillery positions took precedence over all other construction. A representative from the artillery unit due to be employed on the FSB selected the gun positions.
The standard gun pit required a minimum hole of approximately 30 feet in diameter and 3 feet in depth, making it possible to achieve 360-degree coverage by both 105mm and 155mm howitzers. To quickly prepare a gun pit, four 40-pound shape charges were placed 15 feet apart in a square formation, with a fifth charge in the center. Those charges were dual primed with a nonelectric firing system and detonated simultaneously from a single ring main. After the detonations, a 40-pound ammonium cratering charge was placed in the resulting holes and tamped with earth. The cratering charges were also primed nonelectrically and detonated simultaneously to produce a hole approximately 30 feet in diameter and 3 to 4 feet deep, depending upon soil conditions.
A minidozer, the Case 450 Tractor, was then used to clear the pit of loose dirt and shape it to the desired configuration. Dirt from the pit was used to build sandbag parapets around the gun pits. The sides of the pits were lined with sandbags for defensive purposes as well as to prevent erosion, a constant problem during the monsoon season. M-8A1 steel matting was placed in the bottom of the gun pits to provide a stable base for the artillery pieces.
Once this was completed, the artillery pieces and battery personnel arrived by helicopter and the equipment was prepared to accept fire missions. The moment an artillery piece was in position, the forward observer called for a fire mission against an observable target in order to register the guns.
Activity on the FSB was greatly accelerated at this point, making it appear to be a disturbed anthill of activity. While the engineers continued to develop the position by constructing additional parapets, ammunition berms and bunkers, all with connecting sandbagged trenches, the command and staff personnel of the artillery battery were busy establishing their fire direction control centers (FDCCs) as guns and ammunition arrived in rapid succession.
There was no secrecy involved in the creation of an FSB. It was a noisy, major engineering effort, a scene of massive organized confusion with dangerous elements all around. The growling chain saws would sometimes backlash with catastrophic results. When an ax broke, its sharp, heavy head went flying. The flight ended somewhere and was often punctuated by a curse. A cry of "Fire in the hole!" preceded each of numerous explosions. Upon hearing this, the men scattered like startled prairie dogs. Rocks, splinters, limbs, even whole trees rained down through thick clouds of choking, rising dust. The men checked their buddies for injuries, dusted themselves off and began the process again.
Communications And Clearing Out
As soon as the gun pits, FDCCs and other facility bunker locations were designated, a communications detachment was deployed to establish telephone links throughout the firebase. This telephone system was linked to the in-country system via the AN/TRC-97 radio relay system. Hot lines and remote lines were installed and a 24-hour switchboard watch was activated.
The dozers continued to work, scooping out holes that the riflemen and artillery personnel lined with sandbags. A Case 580 heli-liftable, rubber-tired tractor with backhoe attachment was flown in to construct bunkers and ammunition berms. If necessary, they erected columns and set beams for the roof supports. The roof of a bunker consisted of runway matting, sandbags, earth and available trees felled earlier in the operation.
Most engineering personnel and equipment were systematically withdrawn at this point. A small detachment of engineers, however, remained on the FSB to assist in further developing the position through the installation of airfield matting in the landing zones and additional tree cutting on the periphery to ensure that the artillery fire was not masked.
Helicopters taking engineering personnel and equipment out of the newly constructed FSB ferried more infantry arms and equipment in on the turnabout legs. Those deliveries included howitzer ammunition in 100-round lots, fuel and water in 250- and 500-gallon rubber containers, vans for communications and fire direction control, prefab command centers and rations.
Cold Comfort And Rations
The FSB was a makeshift operation. As operations proceeded, empty ammunition crates were broken down and utilized as footpaths. Garbage disposal, although a problem, was never a high priority. Plastic and cardboard wrappings, expended artillery shells and empty C ration cans quickly stacked up. Due to the proximity of large stores of ammunition, engineering explosives and powder charges, trash fires were not allowed on an operational FSB. The trash pits and bunkers were almost immediately infested with legions of mice and rats.
The bunkers were dark and musty. Beds were made of whatever could be scrounged or improvised. There was no paint. There were no windows. Available electricity was reserved for communications and equipment. The new men soon learned that C ration peanut butter made a dim candle. Inside the bunkers the men sweated like pigs, smelled like camels and attracted hordes of voracious gnats and mosquitoes. Insect bites became ulcerated wounds, constantly irritated by salty sweat. Every sore turned into jungle rot.
Mail was infrequently delivered. Hot meals were an event of the past. The men found themselves eating cold C ration spaghetti for breakfast -- and being thankful to have it. There was little water for cooking or shaving and not much more for drinking. Replacement of clothing and other comfort items was given a low priority.
During the monsoon season, a thick green pungent mold grew everywhere. If a FSB was not knee-deep in mud and shrouded by thick cotton-ball clouds of fog, it was almost always baked by an unrelenting sun and obscured by clouds of thick red dirt. In short, FSBs were suppurating wounds gouged out of the emerald flesh of the jungle and bristling with engineering and artillery-aiming stakes, antennae and the long, ugly, dark snouts of artillery pieces pointing skyward -- which periodically snorted flames, sulfurous smoke and death. On top of all that, there was no respite from enemy assaults.
When placed atop a dominant terrain feature, FSBs were defensible, but they were certainly not immune from attacks by enemy infantry and artillery units. Being "fixed" forward positions, established in the enemy's territory by forced entry, FSBs were beacons and quickly became targets for enemy artillery and sapper units.
The attitude of the defenders is typified by the actions of Lt. Col. Charlie Norton, who commanded a battery on Fire Support Base Erskine as a senior captain during a 1969 operation in the A Shau Valley. The fire support base was under constant shelling from enemy 122mm guns in Laos. Quick counterbattery fires and airstrikes that were on time and on target weighted the artillery duels in favor of the U.S. Marines. In spite of enemy spotters, Captain Norton flew his colorful unit guidon as a "professional courtesy" so the enemy would know who was taking all he could dish out and returning the same, with dividends.
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