One time, a group of British commandos tried to sneak behind enemy lines and assassinate Rommel in the North African desert. They failed. But Rommel insisted the commandos be buried in the same graveyard as the German soldiers who died defending him, says Steven Pressfield, author of "Killing Rommel."
There were battle zones during World War II where that type of magnanimity was almost impossible. On the Eastern Front, German and Russian soldiers literally hated one another. And in the South Pacific, U.S. Marines and Japanese soldiers took no prisoners.
At times, the terrain can force soldiers to follow the code. The North African desert during World War II was one such place, Pressfield says.
Fortunes turned quickly because so many battles were fought by fast-moving tanks and mobile units. A German unit that captured British soldiers could end up surrendering to them minutes later because the battle lines were so fluid. Also, the desert sun was so harsh that both sides knew if they left enemy prisoners stranded or mistreated, they would quickly die, Pressfield says.
It was not unusual for German and British doctors to work together while taking care of wounded soldiers from both sides, Pressfield says.
Some British and German soldiers never forgot how their enemy treated them and staged reunions after the war.
"The Germans and the British used to get together for soccer matches," Pressfield says. "It was the Desert Foxes versus the Desert Rats."
These soldiers weren't just engaging in nostalgia. They shared a sense of hardship. They had survived an ordeal that most people could not understand.
"In many ways, a soldier feels more of a bond with the enemy they're fighting than with the countrymen back home," Pressfield says. "The enemy they're fighting is equally risking death."
That bond could even lead to acts of loyalty after the war, says Daniel Rolph, author of "My Brother's Keepers."
Once, when a Union officer mortally wounded a Confederate captain during the Civil War, the Union man sang hymns and prayed with his enemy as the man took his last breaths. Before the captain died, he asked the Union officer to return his sword and revolver to his family -- a request the soldier honored after the war ended, Rolph says.
"I even have an article from The New York Times in 1886 where Union soldiers who were on the pension rolls of the federal government were actually trying to transfer their money toward Confederate soldiers," Rolph says.
These bonds can even form between enemies who do not share a language or a culture.
Harold Moore Jr. was a U.S. Army colonel who led a desperate fight depicted in the 2002 Mel Gibson film, "We Were Soldiers Once ... And Young. " In 1965, Moore lost 79 of his men fighting against a larger North Vietnamese force. It was one of the first major battles in the Vietnam War.
In 1993, Moore led some of his soldiers back to Vietnam to meet their former adversaries on the same battlefield. When they arrived, Moore met the Vietnamese officer who led troops against him, Lt. Gen. Nguyen Huu An.
An held out his arms and greeted Moore by kissing him on both cheeks. Moore gave him his wristwatch as a token of friendship.
Moore described in an essay what happened next:
"I invited all to form a circle with arms extended around each other's shoulders and we bowed our heads. With prayer and tears, we openly shared our painful memories."
An died two years after meeting Moore. Moore traveled to Vietnam to pay his respects to his former enemy's family. While visiting their home, Moore spotted a familiar object displayed in the viewing case of An's family shrine: It was his wristwatch.
A reunion of enemies
As he watched the German fighter peel away that December day, 2nd Lt. Charles Brown wasn't thinking of the philosophical connection between enemies. He was thinking of survival.
He flew back to his base in England and landed with barely any fuel left. After his bomber came to a stop, he leaned back in his chair and put a hand over a pocket Bible he kept in his flight jacket. Then he sat in silence.
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?