He scoured military archives in the U.S. and England. He attended a pilots' reunion and shared his story. He finally placed an ad in a German newsletter for former Luftwaffe pilots, retelling the story and asking if anyone knew the pilot.
On January 18, 1990, Brown received a letter. He opened it and read:
"Dear Charles, All these years I wondered what happened to the B-17, did she make it or not?"
It was Stigler. He had had left Germany after the war and moved to Vancouver, British Columbia, in 1953. He became a prosperous businessman. Now retired, Stigler told Brown that he would be in Florida come summer and "it sure would be nice to talk about our encounter."
Brown was so excited, though, that he couldn't wait to see Stigler. He called directory assistance for Vancouver and asked whether there was a number for a Franz Stigler. He dialed the number, and Stigler picked up.
"My God, it's you!" Brown shouted as tears ran down his cheeks.
Brown had to do more. He wrote a letter to Stigler in which he said: "To say THANK YOU, THANK YOU, THANK YOU on behalf of my surviving crewmembers and their families appears totally inadequate."
The two pilots would meet again, but this time in the lobby of a Florida hotel.
One of Brown's friends was there to record the summer reunion. Both men looked like retired businessmen: they were plump, sporting neat ties and formal shirts. They talked about their encounter in a light, jovial tone.
The mood then changed. Someone asked Stigler what he thought about Brown. Stigler sighed and his square jaw tightened. He began to fight back tears before he said in heavily accented English:
"I love you, Charlie."
Years later, author Makos says he understands why Stigler experienced such a surge of emotions.
Stigler had lost his brother, his friends and his country. He was virtually exiled by his countrymen after the war. There were 28,000 pilots who fought for the German air force. Only 1,200 survived, Makos says.
"The war cost him everything," Makos says. "Charlie Brown was the only good thing that came out of World War II for Franz. It was the one thing he could be proud of."
The meeting helped Brown as well, says his oldest daughter, Dawn Warner.
Brown and Stigler became pals. They would take fishing trips together. They would fly cross-country to each other homes and take road trips together to share their story at schools and veterans' reunions. Their wives, Jackie Brown and Hiya Stigler, became friends.
Brown's daughter says her father would worry about Stigler's health and constantly check in on him.
"It wasn't just for show," she says. "They really did feel for each other. They talked about once a week."
As his friendship with Stigler deepened, something else happened to her father, Warner says:
"The nightmares went away."
Brown had written a letter of thanks to Stigler, but one day, he showed the extent of his gratitude. He organized a reunion of his surviving crew members, along with their extended families. He invited Stigler as a guest of honor.
During the reunion, a video was played showing all the faces of the people that now lived -- children, grandchildren, relatives -- because of Stigler's act of chivalry. Stigler watched the film from his seat of honor.
"Everybody was crying, not just him," Warner says.
Stigler and Brown died within months of each other in 2008. Stigler was 92, and Brown was 87. They had started off as enemies, became friends, and then something more.
Makos discovered what that was by accident while spending a night at Brown's house. He was poking through Brown's library when he came across a book on German fighter jets. Stigler had given the book to Brown. Both were country boys who loved to read about planes.