(CNN) -- The pilot glanced outside his cockpit and froze. He blinked hard and looked again, hoping it was just a mirage. But his co-pilot stared at the same horrible vision.
"My God, this is a nightmare," the co-pilot said.
"He's going to destroy us," the pilot agreed.
The men were looking at a gray German Messerschmitt fighter hovering just three feet off their wingtip. It was five days before Christmas 1943, and the fighter had closed in on their crippled American B-17 bomber for the kill.
The B-17 pilot, Charles Brown, was a 21-year-old West Virginia farm boy on his first combat mission. His bomber had been shot to pieces by swarming fighters, and his plane was alone in the skies above Germany. Half his crew was wounded, and the tail gunner was dead, his blood frozen in icicles over the machine guns.
But when Brown and his co-pilot, Spencer "Pinky" Luke, looked at the fighter pilot again, something odd happened. The German didn't pull the trigger. He nodded at Brown instead. What happened next was one of the most remarkable acts of chivalry recorded during World War II. Years later, Brown would track down his would-be executioner for a reunion that reduced both men to tears.
. . .
Revenge, not honor, is what drove 2nd Lt. Franz Stigler to jump into his fighter that chilly December day in 1943. Stigler wasn't just any fighter pilot. He was an ace. One more kill and he would win The Knight's Cross, German's highest award for valor.
Yet Stigler was driven by something deeper than glory. His older brother, August, was a fellow Luftwaffe pilot who had been killed earlier in the war. American pilots had killed Stigler's comrades and were bombing his country's cities.
Stigler was standing near his fighter on a German airbase when he heard a bomber's engine. Looking up, he saw a B-17 flying so low it looked like it was going to land. As the bomber disappeared behind some trees, Stigler tossed his cigarette aside, saluted a ground crewman and took off in pursuit.
As Stigler's fighter rose to meet the bomber, he decided to attack it from behind. He climbed behind the sputtering bomber, squinted into his gun sight and placed his hand on the trigger. He was about to fire when he hesitated. Stigler was baffled. No one in the bomber fired at him.
He looked closer at the tail gunner. He was still, his white fleece collar soaked with blood. Stigler craned his neck to examine the rest of the bomber. Its skin had been peeled away by shells, its guns knocked out. He could see men huddled inside the plane tending the wounds of other crewmen.
Then he nudged his plane alongside the bomber's wings and locked eyes with the pilot whose eyes were wide with shock and horror.
Stigler pressed his hand over the rosary he kept in his flight jacket. He eased his index finger off the trigger. He couldn't shoot. It would be murder.
Stigler wasn't just motivated by vengeance that day. He also lived by a code. He could trace his
family's ancestry to knights in 16th century Europe. He had once studied to be a priest. A German pilot who spared the enemy, though, risked death in Nazi Germany. If someone reported him, he would be executed.
Yet Stigler could also hear the voice of his commanding officer, who once told him: "You follow the rules of war for you -- not your enemy. You fight by rules to keep your humanity."
Alone with the crippled bomber, Stigler changed his mission. He nodded at the American pilot and began flying in formation so German anti-aircraft gunners on the ground wouldn't shoot down the slow-moving bomber. (The Luftwaffe had B-17s of its own, shot down and rebuilt for secret missions and training.) Stigler escorted the bomber over the North Sea and took one last look at the American pilot. Then he saluted him, peeled his fighter away and returned to Germany.
"Good luck," Stigler said to himself. "You're in God's hands."
. . .
Brown flew more missions before the war ended. Life moved on. He got married, had two daughters, supervised foreign aid for the U.S. State Department during the Vietnam War and eventually retired to Florida.
Late in life, though, the encounter with the German pilot began to gnaw at him. He started having nightmares, but in his dream there would be no act of mercy. He would awaken just before his bomber crashed.
Brown took on a new mission. He had to find that German pilot. Who was he? Why did he save my life?
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.