He was supposed to have been headed home to see his wife. Instead, Colonel Chaicharn Harnnawee spent nine years in captivity during the Vietnam War, learning to tap code through the walls of the Hanoi Hilton and signaling to John McCain.
It was 1965 when Chaicharn, then a sergeant in the Royal Thai Army, was stationed in Laos as a radio operator. A former paratrooper, the then 35-year-old had begun to prepare for his upcoming 10-day leave to see his wife of six years.
Learn more about GOP presidential candidate John McCain tonight: Watch Diane Sawyer's "Portrait of a President" on "20/20" at 10 p.m. ET.
Chaicharn was sent May 21 on a special supply mission to another camp in Laos. With him was American pilot Ernest Brace, who would later be referred to as "America's longest-held civilian prisoner of war in Vietnam."
"[Brace] had volunteered as a civilian pilot to fly supply missions in Laos for the United States Agency for International Development," McCain wrote in his book "Faith of My Fathers," "and, when asked, to secretly supply CIA-supported military units in the Laotian jungle."
Dressed in plain clothes, Brace flew the Thai sergeant and three other passengers --a Laotian solider, a woman and her young child -- on a small plane to Boum Lao village.
They were attacked by gunfire moments after they landed. "He don't know the enemy ambush over there," Chaicharn, now 78, said of Brace from his home, about a two-hour drive from Bangkok.
The solider, woman and child were instantly killed.
Chaicharn and Brace, with a language barrier between them, tried to escape by taking off again, but their engine had been hit and their plane caught fire.
"American pilot he saw [about] that, he get out from the airplane and we run from the airplane to the other side of the enemy in the jungle," Chaicharn said.
Traveling as civilians and with no weapons to protect them, it didn't take long for the two to be surrounded and captured.
"In the front, in the side, in the left, in the right, have many, many," Chaicharn said of the Pathet Lao who caught them and turned them over to the North Vietnamese.
It would be nine years until Chaicharn's wife would see him again -- and eight years before she knew he was even alive.
For 13 days, Chaicharn and Brace were forced to walk high into the mountains to Dien Bien Phu, the location they had overheard from the Vietnamese. At night, both thought by their captors to be from the CIA, their hands and feet were bound to prevent escape.
The two prisoners were held in the jungle of northwest Vietnam in separate small bamboo huts, about two yards long and one yard wide, for more than three years.
They would cough to let each other know they were still alive.
Brace tried to escape three times and once managed to get away for a few days. He was caught, and as a result, they both were punished.
The American pilot was once buried to his neck in the ground for days.
For the time they were held there, Chaicharn said he never saw Brace, but he would hear him and knew he was being abused.
"I heard his voice," he said. "He cried loudly and I knew."
Chaicharn showed how, for years, he was forced in a seated position -- his legs locked into holes cut in a piece of wood, his neck held back in place with iron piping and his hands tied together with rope.
They had two 15-minute breaks a day, were fed rice and ate "no meat, no pork, no egg, no fish," the Thai POW said.