During World War I he was not a member of the Lafayette Escadrille as some historians write. A hapless namesake who served briefly in the famous Lafayette Escadrille suffered several mishaps and left the service.
He is most famous for organizing and leading (as a colonel) the so-called Doolittle Raid in 1942 which was a daring carrier-based bombing run against mainland Japan following the American defeat at the Battle of Pearl Harbor. The bombers didn't have enough fuel to return home and most were forced to ditch in China.
Doolittle was awarded the Congressional Medal of Honor for accomplishing this mission, which is viewed by historians as a major public-relations victory for the United States. Although the amount of damage done to Japanese war industry was minor and quickly fixed, the raid showed the Japanese their homeland was not invulnerable, and forced them to withdraw several frontline fighter units for homeland defense. President Franklin D. Roosevelt presented the medal to Doolittle.