BOCA RATON, Fla. -- A former U.S. prisoner of war jailed in a Vietnamese prison next to John McCain is remembering the late senator's heroism and humor.

• Melvin Pollack, John McCain met at Hanoi prison camp
• They were both shot down while serving in Vietnam
• 'He had a tremendous impact. He was a real maverick,' Pollack says of McCain
• RELATED: Sen. John McCain remembered Thursday at service

Melvin Pollack retired as a lieutenant colonel from the U.S. Air Force after a 25-year career. 

Pollack first met McCain through the thin brick walls of a Hanoi prison camp in 1967. The pair was held by the North Vietnamese in Hoa Lo, a prison sarcastically called the "Hanoi Hilton" by captured U.S. service members. 

"They didn't treat us well, but we couldn't make them understand our war was over. We didn't know operational plans, we didn't know what was happening," Pollack said.

At his death, McCain had served his country for more than 60 years. He followed in the footsteps of his father and grandfather when he joined the U.S. Navy. 

McCain eventually became a Navy aviator, assigned to combat missions during the Vietnam War. 

In October 1967, North Vietnamese soldiers used missiles to shoot down McCain's Skyhawk aircraft. 

"I was gyrating very violently, almost straight down," McCain once recalled. "I had to eject very quickly."

Pollack at the time was a 25-year-old Air Force combat pilot when he, too, was shot down July 6, 1967. 

"Everything came off the airplane," Pollack said. "There were two pilots. We both ejected at about 22,000 feet and 600 knots."

Pollack, McCain learn about each other's lives

Hoa Lo was infamous for its harsh conditions. 

"Putrid yellow, concrete bed boards with leg irons," Pollack said.

At its peak, 591 U.S. service members were held as prisoners of war in Vietnam; most of them were regularly beaten and abused by guards.

McCain was seriously injured after his crash. 

He was only given medical treatment after his captors learned McCain's father was a high-ranking Navy admiral, in charge of Pacific Command.

He was eventually sent to a cell next to Pollack. 

"We were in this small cell across the wall from John, who was in isolation, and as I recall, in a partial body cast still. That's how we met," Pollack said.

For months, the two would talk through the walls, using cups and towels to talk back and forth. 

"We talked for hours every day ... (about) everything, where you were born, what you did, did you go to school," Pollack said. "You have nothing but your mind. There's no outside stimulus. You're locked up in this prison cell, and you get out maybe once a day for short periods of time."

It was through that wall that their friendship grew. 

When McCain was offered an early release, he refused. 

"When John was offered, he was really hurting, but he upheld the Code of Conduct," Pollack said.

The Code of Conduct is a vow that prisoners of war would only be released in the order in that they were captured.

Peace agreement leads to release in 1973

A peace agreement eventually led to the release of the almost 600 prisoners of war in Vietnam.

Pollack was part of a group released on March 4, 1973, McCain a few days later on March 14.

Their regained freedom also gave the friends a chance to meet face-to-face for the first time.

"He put his arm around me and he said, 'Your sense of humor saved my life.' I couldn't believe it," Pollack said. "I said, 'You have the sense of humor, not me.' "

Both men spent more than 5 1/2 years locked up in Hoa Lo.

Back home in the U.S., Pollack returned to his career in the Air Force, while McCain set his sights on Congress.

McCain served as a senator from Arizona from 1987 until his death Aug. 25. 

"He had a tremendous impact. He was a real maverick," Pollack said. 

The two kept in touch over time as best they could. Pollack said he last saw McCain in 2016 when the senator was in South Florida fundraising for his Senate re-election campaign.

Pollack said McCain has always been a man dedicated to serving his country and putting others before himself. 

"He's a great guy, absolutely. He's a genuine guy, and we're going to miss him. We really need him at this time," Pollack said.