By LEE FERRAN and JAMES GORDON MEEK

After a legendary Special Forces officer was pushed out of the military over a frontline romance with a Washington Post reporter, along with the use of illicit pain pills and booze, Maj. Jim Gant recently found he had a powerful supporter in former CIA Director Gen. David Petraeus - a man familiar with the consequences of personal scandal.

"Jim [Gant] was the complete package when you consider what you're looking for in a Green Beret, [a] Special Forces team leader. He was… the perfect counter-insurgent," Petraeus told ABC News in a rare on-camera interview. "He was a master."

"We asked a great deal of this individual. He'd provided a great deal. And frankly to see his career end the way it did was painful to hear about," Petraeus said.

Top Green Beret Officer Forced to Resign Over Affair With WaPo Reporter

PHOTOS: The Rise and Fall of Special Forces Officer Jim Gant

FULL COVERAGE: Jim Gant, Lawrence of Afghanistan

Maj. Jim Gant was a highly-decorated Green Beret who in 2009 wrote a 45-page pamphlet called "One Tribe at a Time," a strategy that called on American Special Forces to, as he calls it, "go native" - to dress like, live like, fight like and, if necessary, die like the Afghan villagers he felt were critical to turning the tide against the Taliban.

Petraeus, who took command of American forces in Afghanistan in 2010, agreed with Gant and made sure Gant's next deployment was in Afghanistan where he could put the strategy to use. And, for a while, it looked like it could be the key to gaining ground in the protracted conflict.

"I never like to use the term winning or losing," Petraeus said. "I just like the term progress. And we were clearly making progress in his area… I went to see Jim and to spend time with him in his element… I was hugely impressed… He was doing a superb job."

Gen. Petraeus, second from left, meets with Maj. Jim Gant, second from right, in Afghanistan in 2010. (Courtesy Chief Petty Officer Joshua Treadwell, U.S. Navy)

But as detailed in a recent ABC News investigative report, Gant went too far, leading some to compare him to the mad Col. Kurtz from the Vietnam War film Apocalypse Now.

He was demoted and then he retired from the military in 2012 after the brass found out he had been living with a lover - prominent Washington Post reporter Ann Scott Tyson, who had left the Post and later wrote a book about Gant - on the frontlines in Afghanistan for nearly a year. Gant and Tyson, who were both married when they met, were separated from their spouses and later married each other. Gant also admitted to drinking and taking pain pills while deployed, both against military regulations.

DOCUMENTS: Letter of Reprimand | Gant's Response

Petraeus said he was "disappointed" to watch Gant's fall from grace.

"He clearly took actions that were not in keeping with the standards and he paid a very high price," Petraeus said.

On some level, Petraeus knows that price. After a meteoric rise to the highest levels of the military, Petraeus was tapped to run the CIA in September 2011. But just over a year later, he resigned from the job after publicly admitting he had engaged in an "extramarital affair." The reserved military man became tabloid fodder.

Since, Petraeus has for the most part dodged the media spotlight. But he sat in front of ABC News cameras again for Gant.

"He clearly had grit. He had guts. He had intelligence. He was courageous… He is one to whom we owe a debt of gratitude, even recognizing how things ended for him," Petraeus said. "Folks make mistakes, obviously."