Each mission was different, depending on the technology. Sometimes the OP-2E Neptunes had to fly in low and level over the trail, as was the case when crews were dropping listening devices called acoubuoys. Each sensor was jettisoned from the aircraft with its own small parachute attached. Aircraft needed to fly low on these missions because too much altitude raised the likelihood that the parachute lanyards would get tangled up in too much air and fail to emplace themselves in the canopy of trees. But flying low and level made them an easy target for the Vietcong antiaircraft guns that were so prevalent along the trail.
Other missions involved sensors that had to be dropped from a higher altitude, around five thousand feet. This was the case with Crew Seven’s mission today. They would be dropping Air Delivered Seismic Intrusion Detectors, or ADSIDs. The seismic devices were made by Sandia weapons laboratory for ARPA and were based on technology developed for an earlier ARPA program, Vela Hotel, which involved ground sensors for detecting nuclear tests. The ADSID sensors were approximately two and a half feet long and five inches in diameter. Each one looked like a miniature missile, or a large dart, with tail spikes that were released outward once the ADSID was lodged firmly in the ground. ADSIDs were designed to penetrate the earth from a high speed and to be deployed from the OP-2E without a parachute.
Standing on the tarmac preparing for the mission, Rip Jacobs was ready. He double-checked his parachute. Then he climbed aboard the aircraft.
Crew Seven left the tarmac on time. Roughly an hour into the mission, Captain Milius reported his position not far from the Ban Karai Pass. Rip Jacobs was standing near the deck hatch, observing ordnance drops. Ensign Tom Wells was seated in a well-armored chair, with his face in the Norton bombsite, calling out coordinates when suddenly the aircraft was engulfed in flames. “That’s how it happens,” Wells explained in 2013. “You’re flying fine, then wham, you’re hit.”
An antiaircraft projectile fired by the Vietcong had come up through the bottom skin of the airplane and exploded in the radar well. “Now everything was on fire,” Wells recalled. “I grabbed the fire extinguisher next to the hydraulic panel, but it was on fire. It burned the skin off my hands.” In a matter of seconds the flight deck area was filled with dense, dark smoke.
Lieutenant Barney Walsh, the co-pilot, climbed out of his seat and started to make his way to the back. “We couldn’t control anything” in the cockpit, he says. “I’m yelling ‘Get out!’ That was the only choice. That was it.” Someone else hollered, “Hatch open, parachutes ready to go!”
There was blood everywhere. In the chaos, Rip Jacobs tried to ascertain what was going on. Then he realized Petty Officer John F. Hartzheim, an avionics technician, had been hit badly.
“He wasn’t wearing his parachute,” Wells says.
“He had taken it off because it was so hot,” Jacobs explains. “He was bleeding badly. Mortally wounded. I thought about trying to get a parachute on him. The smoke and flames were so intense. The G-forces. I was standing in a pool of [Hartzheim’s] blood and I slipped and fell down on the floor. The plane was going down. In your mind you’re saying, ‘With the last crew, nobody got out.’”
Someone hollered again. “Parachutes, get ready. Go!”
Rip Jacobs turned to the deck hatch. He jumped out of the burning airplane and began to fall. He pulled his ripcord. The chute opened. What happened after that he can’t get his memory to recall. Time passed. Was he dead? After a while he realized he had landed in a tree.
“I was alive. Everything hurt. Back. Legs. I looked down and I was covered in blood.” The way he had landed in the tree canopy, his body was parallel to the ground. The parachute lanyards had wrapped around him in a way that made it impossible for him to wriggle free. “Did I remember to hit my locator button when I was falling through the air?” He asked himself this question again and again.
He tried to reach the button with his chin. It was out of reach.
“I was pretty sure I’d set off my locator button,” Jacobs recalls. “But what if I didn’t? What if I hadn’t activated the locator? I’d die up here. What if no one knows where I am?”
Then a worse thought. He heard sounds. The unmistakable sound of gunfire. Single shots. One after the next. Getting closer. There were Vietcong on the ground looking for VO-67 crewmembers who had made it out of the burning airplane they had just shot down. More gunfire. What if the Vietcong spotted him up here in this tree?
“I had to be real quiet,” Jacobs recalls. “Every time I tried to move at all, all the dead stuff around me fell to the ground.” During missions, there were F-4 Phantom fighter jets that protected the OP-2E Neptunes from any approaching enemy MiGs. “One [F-4] flew over the top of my head. Did he see me?” Three, maybe four hours passed. “It felt like eternity.”
Suddenly, Rip Jacobs heard the faint sound of a helicopter. Or was he imagining things? Then he was certain. He was hearing the unmistakable sound of helicopter blades. A Jolly Green. He saw it in the distance. A rescue team. Then a crushing thought. “What if it didn’t see me? What if it was out searching a wide area?” If he hadn’t hit his locator button, no one would know he was here in this tree.
And then, out of the corner of his eye, he saw the helicopter slow down. Slower. Closer. The Jolly Green was hovering overhead.
Out of the helicopter came a Pararescue crewman. The man was sitting on a little seat attached to a metal cable. The cable got longer and the man got closer as he was lowered down to where Rip Jacobs was tangled up in the tree.
“He reached out to me. I saw his two arms. Then he folded down this little seat next to his seat. He pulled out a knife and cut me from the shroud lines.”
Rip Jacobs climbed onto the seat beside the Pararescue crewman. “I never talked to him. The helicopter was deafening. We were extremely high up. Adrenaline was pumping through my body. I was covered in blood.” Jacobs was pulled into the Jolly Green. “There were medical people inside. They told me I was bleeding badly, but mostly I was covered in Hartzheim’s blood.”
The Jolly Green made its way back to Nakhon Phanom Air Base. Once the helicopter touched down, hundreds of people swarmed out onto the tarmac. It seemed like everyone from the VO-67 Navy squadron was there. It was overwhelming, Jacobs recalled. “To go from that terrified to that relieved.” He was taken into a room for a debriefing. Hartzheim had died in the aircraft. Captain Milius was MIA, missing in action. Everyone else made it out alive and was rescued by now. “An Air Force officer started asking me a lot of questions. It took a moment to register that he was asking about the sensor devices. The devices were laid out in a string, with timing. He kept asking about the devices. I kept thinking I could care less about where those things went right now. But he kept talking about the devices. It was absurd.”
At the time, Rip Jacobs had no idea that the sensor technology program he was part of was the highest-priority program of the war. He had no idea that the top secret program had cost well over $1 billion to bring from conception to fruition. Or that it was the brainchild of the Jason scientists—an idea they had come up with less than two years before, during a Jason summer study in Santa Barbara in 1966.
The Jasons called their idea the “Anti-Infiltration Barrier.” The Pentagon gave it a series of code names as it transitioned from theory to reality. First it was called Project Practice Nine, then Illinois City, then Dyer Marker, then Igloo White and Muscle Shoals. After the war was over and parts of the program were made public, it would become known—and often ridiculed—as McNamara’s electronic fence.
The electronic fence idea was born in the summer of 1966, shortly after the Jason scientists completed the study about whether or not the Pentagon should use nuclear weapons to cut off weapons traffic along the Ho Chi Minh Trail. The Defense Department was desperately seeking new ways to win the Vietnam War. The bombing campaigns were failing. ARPA’s Project Agile was having no effect on the communist insurgency. Weather warfare wasn’t working. Nuclear weapons were not a
n option. Soon there would be 385,000 U.S. military personnel in South Vietnam. And yet despite these numbers and the efforts of so many involved, Ho Chi Minh’s men and matériel kept pouring down the Ho Chi Minh Trail in a steady, unrelenting stream.
Secretary McNamara wanted an unassailable solution, and he looked to the Jason scientists to help figure out a way to sever the trail’s arteries. Their idea involved creating a series of electronic barriers across major access routes along the Ho Chi Minh Trail, so-called “denial fields,” running through central and eastern Laos, into Vietnam. The Jasons proposed to bug the battlefield so as to be able to “hear” what was happening on the trail, then send in strike aircraft to bomb Vietcong troops and truck convoys on the move.
As ARPA’s head of counterinsurgency, Seymour Deitchman organized the Jason summer study and then flew out to Santa Barbara to oversee efforts. Secretary McNamara personally made sure that General Maxwell Taylor and William Sullivan, the U.S. ambassadors to Vietnam and Laos, traveled to Santa Barbara to brief the Jasons on the Pentagon’s electronic barrier idea. The ambassadors’ presence that summer underscored just how badly the Pentagon needed the concept to work, even if the diplomats thought privately that the fence was a foolish idea. “Secretary McNamara asked me if I would go out with General Taylor, to talk to the Jason group out at Santa Barbara, where they were working on some electronics,” Ambassador Sullivan later recalled. “Neither Taylor nor I thought very much of it. My expectations of it were never very high.”
The electronic fence had two faces, one public and one classified. The program that the public would be told about was a physical fence or barrier that was being constructed by the Pentagon to disrupt traffic on the Ho Chi Minh Trail. This fence would be built by Army engineers and guarded by Army soldiers. “A mechanical barrier built of chain link fencing, barbed wire, guard towers, and a no-man’s land,” as Jason scientist William Nierenberg later described it. But the secret fence the Jason scientists were to design required no soldiers to keep guard. Instead, high-technology sensors would be covertly implanted along the trail.
Since their creation in 1960, the Jason scientists had been involved in many of the most classified sensor programs ARPA initiated, including the Navy’s development of sonobuoys and magnetic detectors, Sandia’s development of seismic sensors, and the Army’s development of infrared sensors. Now, during the 1966 summer study, the Jason scientists developed a plan to fuse, or merge, various sensor technologies and to make them work together as a system, borrowing anti-submarine warfare tactics used by the Navy. Except instead of listening for Soviet submarines in a vast ocean expanse, the anti-infiltration barrier would listen for Vietcong fighters in a sea of jungle trails.
The prototype for the Santa Barbara summer study was ARPA Study No. 1, also called Project 137, which had taken place at the National War College at Fort McNair in Washington, D.C., in the summer of 1958. This time, in Santa Barbara, the scientists lived in University of California dormitories looking out over the Pacific Ocean. In the mornings, they gathered in a university lecture hall for daily briefings. They wrote reports in the afternoon and gathered together again in the evening for dinner and to share ideas. They studied history’s great barriers and walls built over the previous two thousand years, from the walls around Jerusalem, to the Great Wall of China, to the Nazis’ Siegfried Line. During breaks, Murph Goldberger recalled playing tennis. The particle physicist Henry Kendall surfed in the Pacific waves. The nuclear physicist Val Fitch and the experimental physicist Leon Lederman took long walks around the campus grounds. It was an interesting idea, this electronic fence. But could it be done?
The Jasons produced a classified study called Air-Supported Anti-Infiltration Barrier. In it, they concluded that an electronic fence could in fact be built across and along the Ho Chi Minh Trail. The barrier would be constructed of the most advanced sensors available in the United States, including audio and seismic sensors, but also thermal, electromagnetic, and chemical sensors designed to detect fluctuations in body heat, engine heat, and even scent. Initially, these sensors would be implanted along the trail by being dropped out of aircraft, like the OP-2E Neptune, flying low over the trail. Some of the small, camouflaged sensor packages would be carried down to the ground by small parachutes, while others would be jettisoned into the earth like spears. The idea was that enemy troops moving down the trail would trigger these sensors with movement or sound. The sensors would in turn relay the information to overhead reconnaissance and surveillance aircraft, which would in turn relay the information to the “brain” of the program—a room full of computers inside a highly classified Infiltration Surveillance Center, most likely at a U.S. air base in Thailand.
Computers would play a key role, the Jason scientists imagined. The machines would analyze and interpret the sensor data. Technicians would then use the information to pinpoint the exact locations of communist fighters, trucks, and other transport vehicles, including bicycles and oxen carts. Military commanders would then dispatch aircraft to drop SADEYE cluster bombs on jungle fighters moving down the trails. These unguided, or “dumb,” bombs each carried a payload of 665 one-pound tennis-ball-sized BLU-26B fragmentation, or “frag,” bombs, each with a delay fuse that allowed the submunitions to blow up just above the ground, spraying razor-sharp steel shards in a kill radius of roughly eight hundred feet. Jason scientist Richard Garwin, a nuclear physicist and ordnance expert who, years before, helped design the Castle Bravo hydrogen bomb, held a seminar on the SADEYE cluster bomb and other munitions that would be most effective when accompanying the sensors on the trail. The Jason scientists determined that the trail should be seeded with button bomblets, small, “aspirin-size” mini-bombs designed to make a firecracker-like noise when stepped on, thereby triggering the air-dropped acoustic sensors. Two anti-truck bombs were also included in the design, coin-sized “Gravel mines,” and larger land mines called Dragontooth mines, so named because they looked like giant teeth. These anti-truck bombs were designed to damage vehicle tires, which would slow convoys down and give strike aircraft more time to hit their targets. When stepped on they were powerful enough to remove a person’s foot.
The electronic fence concept was a colossal undertaking with many moving parts. The Jason scientists were very specific regarding the numbers of bombs it required: “20 million Gravel mines per month; possibly 25 million button bomblets per month; 10,000 SADEYE-BLU-26B clusters per month,” the sum total of which made up “by far the major fraction [of what] has been estimated to be about $800 million per year” in operational costs alone. “It is difficult to assess the likely effectiveness of an air-supported barrier of this type,” the Jasons concluded in their written report. “We are not sure the system will make the [trail] nearly impenetrable, but we feel it has a good claim of being the foundation of a system that will, over the years.” Finally, a prescient warning: “We see the possibility of a long war.”
With the work complete, the summer study came to an end. On September 1, 1966, Goldberger, Deitchman, and several other Jasons flew to the Pentagon to brief Secretary McNamara on their final proposal for an electronic fence. The projected costs had risen to roughly one billion to get the fence up and running, they said, and it could be constructed in about a year and a half. McNamara was impressed.
Meanwhile, that same summer, Secretary McNamara had assembled a second group of scientists on the east coast—made up of Jason scientists and non-Jason scientists from Harvard and MIT—also working on the electronic fence idea. This group, called Jason East, conducted its work on the campus of Dana Hall, a girls’ school in Wellesley, Massachusetts. The two study groups were given similar information, classified and unclassified, and came up with likeminded ideas about what would work best on this fence project and why. Pleased with both sets of results, McNamara merged the two studies into one.
A second briefing took place on September 6, 1966, this time at the Cape Cod summer home of Jason East member Jerrod Zacharias.
Secretary McNamara, Assistant Secretary of Defense John McNaughton, and Director of Defense Department Research and Engineering John Foster (who, like his predecessors Herb York and Harold Brown, had served as director of the Livermore laboratory before working at the Pentagon as the liaison between ARPA and the secretary of defense) helicoptered in to the meeting on Cape Cod. Gordon MacDonald represented the Jason group at the secret briefing. “The occasion was highly informal,” he remembered, in one of the only known written recollections of the meeting. “Maps were spread out on the floor, drinks were served, a dog kept crossing the demilitarized zone as top secret matters were discussed. Even though the subject was the Jason study, I was the only Jason present.” Seymour Deitchman did most of the talking. “It was, you know, a typical social occasion,” MacDonald recalled, except the participants were “just… deciding the next years of the Vietnam War.”
But at the Pentagon, McNamara’s electronic fence idea was belittled by most of the generals. When McNamara sent the final Jason study to General Earle Wheeler and the Joint Chiefs of Staff for review, they rejected the idea. General Wheeler thought it was too expensive and feared it would pull valuable resources away from the front lines. “The very substantial funds required for the barrier system would be obtained from current Service resources thereby affecting adversely important current programs,” General Wheeler wrote in his response. Admiral Ulysses Sharp, commander in chief of the Pacific Command (CINCPAC), saw the entire construction effort as “impractical.” The Joint Chiefs felt that McNamara’s electronic fence idea would require too much time and treasure, and relied too heavily on technology, some of which did not yet exist. “It [is] CINCPAC’s opinion that maintenance of an air supported barrier might result in a dynamic ‘battle of the barrier,’ and that the introduction of new components into the barrier system would depend not only on R&D and production capability, but would also depend on the capability to place the companions in the right place at the right time.” It was simply too complicated—not just to implement but to create. “CINCPAC concluded that even if the US were to invest a great deal of time, effort, and resources into a barrier project, it was doubtful that such a barrier would improve appreciably the US position in RVN [the Republic of Vietnam].” The commander of Military Assistance Command, Vietnam, kept his opinion succinct: “It is necessary to point out that I strongly oppose commitment to create and man a barrier.”