Out of a unit of 28 radio operators sent to Vietnam in 1966, only two made it home alive. They had the shortest life expectancy of anyone in their unit. Yet, they carried what was described as the most important tactical item of the war. Their story is far more horrific than it first appears.
And now you’re going to see why. Vietnam was unlike the wars that came before it. Instead of massive battles with clear front lines, it was a war of sudden ambushes and constant skirmishes. Most firefights happened at close range with 80% of engagements taking place within 200 m. 90% of those fights were initiated by the Vietkong who struck first and vanished into the jungle.
For US soldiers, that meant living in a state of permanent tension. While a World War II infantryman might have faced 40 combat days in a year, the average soldier in Vietnam endured 240. In this environment, the ability to quickly call for reinforcements or firepower often determined whether US units survived and the radio telephone operator or RTO for short played an essential role for American forces.
Without him, a platoon was cut off. It was the radio man who made possible the first helicopter war. gunship fire support, rapid troop withdrawals, and life-saving medevac. To do this, the RTO relied on the most widely used radio of the war, the prick 25, which was first tested in 1964.
General Kryton Abrams, commander of military assistance command Vietnam, called it the most important tactical item in Vietnam today. And he was right. For the duration of his 13-month tour, the RTO carried it on his back. He was the infantry’s only voice, connecting platoon in the jungle to the vast network of American firepower in the air and on the ground.
The radio looked simple. Two stacked metal cans. The bottom held the battery pack. The top held the transceiver. It weighed just under 14 lb without batteries. With batteries and spares, it was over 54 lb. On top of that, the RTO carried an M16, ammunition, cantens, and other gear. All of which had to be lugged through the wet mud-filled rice patties of the Delta.
They could never walk in straight lines and instead slogged and stumbled their way through. Despite its weight, the Prick 25 was highly capable. It provided 920 channels and could communicate roughly 6 mi with its short 3-FFT antenna or up to 20 m with the 10-ft fishpole longrange antenna. The system was extremely easy to operate and maintain.
All the operator had to do was to select a radio frequency, a transmitter power level, and one of two selectable noise reduction modes, and then hook up an antenna and handset, and he was operational. The radio was also durable and waterresistant, but its antenna was impossible to hide. RTO’s called it the shoot me stick for a reason.
Vietkong troops quickly learned that taking out the man with the antenna meant silencing the radio and cutting the platoon off from air support, artillery, and evacuation. Adding to this danger, these early radios had no encryption. Despite RTO procedures to assure broadcast security and numerous warnings from the Army Security Agency that their radio networks were being intercepted, American forces typically refused to believe the warnings or take any action.
Perhaps the most painful example of how intercepted radio signals affected US operations occurred in the first major clash between American forces and the North Vietnamese. In mid- November 1965, 500 troopers of the First Cavalry Division under Lieutenant Colonel Hal Moore were inserted by Huey helicopters into a small landing zone in the Ear Drang Valley in South Vietnam’s central highlands.
The site was named LZ X-ray. X-ray was near the Chu Pong Mountain dominating the valley at an altitude that enabled US communications during the fight to be easily monitored by an NVA radio intercept organization. Moore did not know that the NVA would monitor more than 28,000 radio transmissions during the 3-day battle that saw 234 American lives lost and hundreds more wounded.
The enemy monitoring effort revealed the location of LZ X-ray and the fact that there were only enough helicopters available to lift one company of Moor’s battalion into the landing zone at a time. With that intelligence, the enemy force attacked the first troop lift immediately after landing, isolating platoon size units and causing heavy casualties.
As the rest of the battalion flew in peace meal, each lift was attacked in turn, resulting in the US force being surrounded and nearly wiped out. The only thing that saved the first battalion from destruction was artillery support from surrounding firebases, close air support, and the grit and determination of Moor’s troopers. Reinforcements from the second battalion, seventh cavalry, and second battalion, fifth cavalry finally allowed US forces to beat back the NVA and VC.
Moore and the battered first battalion were lifted out from LZX-Ray. But the battle was not over. No one knows how many lives were lost in Vietnam due to poor communications security. But the number certainly far exceeds the muchtalked about losses due to friendly fire and non-combat related deaths. Beyond intercepted communications, the RTO’s faced immediate danger in combat, especially during helicopter insertions when commanders and their RTO’s often drew fire the moment their boots hit the ground. The radio operator always stayed
close to the officer in charge, placing two critical targets side by side. To the Vietkong, a man with a whip antenna sticking from his pack was more than just another soldier. He was the key to denying American units the overwhelming advantage of air power. The antenna itself added another layer of danger.
On patrol in the jungle, it could catch a trip wire in the trees above, triggering a hidden booby trap when an American unit stumbled into enemy contact and bullets cracked overhead. The platoon leader had only seconds to make decisions that meant the difference between survival and annihilation. The instinct was to fire back, but just as vital was the call for artillery.
It was the RTO’s job to make sure that call went through clearly, even as gunfire roared, men shouted, and the dense terrain made it nearly impossible to pinpoint their exact position. The artillery observer had pre-planned fire zones marked on a map, but how close the platoon was to those fire zones was always a dangerous unknown.
To reduce the risk, platoon leaders often asked for the first round to be smoke, listening carefully to hear where it landed and praying it wasn’t on their own men. From there, the RTO relayed adjustments, carefully adjusting the fire to keep the platoon safe. When ambushes left soldiers bleeding out, the pressure on command intensified.
Attack the enemy or call for a medevac. In the thick canopy, Cobra gunships were useless. They couldn’t even see the men on the ground. Smoke signals failed too. Caught in the tree canopy above. As medics scrambled to stabilize the wounded, the RTO called for medevac, sending out coordinates that were often only rough guesses.
Desperate for visibility, soldiers hacked down trees to open a hole in the canopy. When the sound of rotors finally swept overhead, the RTO spoke directly with the pilot. When spotted, the medevac swooped in low, hovering just long enough to lower a jungle penetrator, a steel cable with a seat on the end.
The wounded man was strapped in and hauled skyward, and only then could the platoon breathe easier as it was a short flight to the battalion aid station. The same urgency applied to air assaults, where timing had to be exact, because even a few minutes delay gave North Vietnamese forces time to melt away into the jungle or set traps for an ambush.
The NVA and VC studied American tactics closely, even learning to mimic the color-coded smoke grenades used to mark landing zones or signal air strikes. In the fog of war, with battles shifting by the minute, radio communication was the lifeline, the only way to outmaneuver an enemy who was always watching and adjusting. The stakes for RTO’s were deadly.
One RTO, Jim Shingleton, recalled that out of 28 radio operators in his unit, 26 were killed within a week. Yet for all the risks, the RTO remained indispensable. To improve both security and survivability, the Prick 77 was eventually developed, replacing the Prick 25 and adding encryption for squad level communications.
This innovation later led to Syncgar’s radios which used frequency hopping to resist jamming and interception.
