The Viet Cong soldiers would hide in underground tunnels, and this was a serious problem in Vietnam. Cu Chi, where Brown was stationed, was famous for its tunnels. The Americans were afraid the Viet Cong soldiers would tunnel into their compound at night. The tunnels were such a problem that Brown spent a lot of time thinking about it and came up with a way to detect them.
It was such a simple idea that anyone could learn to do it in five minutes. He took about fifteen feet of long, skinny cleaning rods for rifles. (Thousands of them were sitting in the warehouses he supervised. They were about a foot long and could be screwed together to any length desired.) At the end of this fifteen-foot rod, he had machinists fabricate a large, sharp tip. A soldier would push the rod into the ground, and if a tunnel was underneath, there would suddenly be no resistance and the rod would pop through. A tunnel was confirmed by squirting in water from a hand-operated fire extinguisher and listening for the splash of water on the bottom of the tunnel. If the water squirted back in your face, it wasn’t a tunnel.
Another invention of Brown’s was an anti-mine device. He saw the gruesome destruction from the mines that the Viet Cong planted in the roads. He was haunted by the sight of an armored personnel carrier blowing up with eleven men inside and seeing the flesh hanging from the walls of the wreckage. Something had to be done about the mines, Brown thought. With the help of some welders in the unit, he built a device to be pushed by a tank recovery vehicle. The mine was set off by the device—not a tank or person. The device was heavy enough to set off a mine, but weak enough to break cleanly at a few joints so the mine damaged only part of the device. Then the soldiers could rebuild it quickly with spare parts that they carried.
This anti-mine device was getting better with each prototype Brown built. But a new commander came in and told him to stop his side projects. Brown wasn’t neglecting any of his duties, and he felt that this mine detector was very important. But the commander thought Brown was eating up resources and needed to focus on his assigned duties.
It was a great disappointment for Brown to give up those projects. Sometimes he felt he should have stayed in Vietnam and perfected his anti-mine device and taught more units to detect tunnels. Some encouraged him to volunteer for a second year and go to a unit that did nothing but scientific work. But Peggy was home with the three little children, and Brown needed to go home. He also wondered how many other superiors would squelch anything innovative or want him to do only what made them look good.
So he left Vietnam after his one-year assignment, but he could never get the people out of his mind. Later when America pulled out of Vietnam, Brown was troubled. He worried about Lam Van Hai because he had been friendly to the Americans. Brown knew about the concentration camps for those who helped the United States. He would often talk to Peggy about Hai and wonder what had happened to him. Year after year he couldn’t get him out of his mind. But there wasn’t any word from Hai.