From Cracked.com:

In 1942, when he was just 12 years old, Arkady Kamanin begged his dad, a commander and decorated war hero in the USSR Air Force, to  let him enlist, so Arkady’s father let him join up as a mechanic.

 After mastering the ins and outs of Soviet planes, Arkady got promoted to flight mechanic and navigating officer. That’s the guy who’s just supposed to sit in the back seat of the plane and fix anything that goes haywire, but while on a mission in 1944, Arkady’s pilot was hit by a bullet. Arkady mustered up courage and, with some guidance from the crew on the ground, he landed the plane perfectly. This understandably impressed Arkady’s dad, who then allowed his son to go into flight training. Two months later, Arkady became the youngest fighter pilot in World War II.  

 Once, while returning from a patrol flight, Arkady spotted the smoking wreck of a Soviet U-2 plane, landed his own craft while enduring heavy German fire and rescued the pilot, along with the sensitive information he was carrying. He was awarded the Order of the Red Star, the Soviet version of the Congressional Medal of Honor. 

By war’s end, Arkady had racked up an impressive list of commendations. He received “two combat Orders of the Red Star, the Order of the Red Banner, the Medal for the Victory Over Germany in the Great Patriotic War 1941-1945, the Medal for the Capture of Budapest and the Medal for the Capture of Vienna.” All by age 14.