A challenge coin is a small coin or medallion (usually military), bearing an organization’s insignia or emblem and carried by the organization’s members.
They are also exchanged in recognition of visits to an organization.
Before the entry of the United States into the war in 1917 American volunteers from all parts of the country filled the newly formed flying squadrons.
Some were wealthy scions attending colleges such as Yale and Harvard who quit in mid-term to join the war.
In one squadron, a wealthy lieutenant ordered medallions struck in solid bronze and presented them to his unit.
One young pilot placed the medallion in a small leather pouch that he wore about his neck.
Shortly after acquiring the medallion, the pilot's aircraft was severely damaged by ground fire.
He was forced to land behind enemy lines and was immediately captured by a German patrol.
In order to discourage his escape, the Germans took all of his personal identification except for the small leather pouch around his neck. They sometimes masqueraded as civilians and wore civilian clothes.
In the meantime, he was taken to a small French town near the front. Not recognizing the young pilot's American accent, the French thought him to be a saboteur and made ready to execute him.
Taking advantage of a bombardment that night, he escaped. He succeeded in avoiding German patrols by donning civilian attire and reached the front lines. He had no identification to prove his allegiance, but he did have his leather pouch containing the medallion.
He showed the medallion to his would-be executioners and one of his French captors recognized the squadron insignia on the medallion.