In the early 1940s, the name "Fei Hu" or "Flying Tigers" was given to the American Volunteer Group by the Chinese media and the title soon gained worldwide attention. The AVG pilots flew the Curtiss P-40 Warhawk in defense of China against Japanese invaders. Flown in the China-Burma-India Theater, the P-40 was first used by Claire Lee Chennault’s American Volunteer Group. It was later flown by American and Chinese pilots of the Tenth and Fourteenth Air Forces. P-40s dominated the skies over Burma and China.

The P-40, with the dreaded sharks mouth painted on its cowling, became one of the most enduring images of World War II. With a combat record comparable to the best fighters of its era, it became a symbol of the American war effort, captivating the minds and hearts of the American public as it continues to do to this day.

In 1937 the rescue patch, or blood chit as it was commonly called, was issued to Flying Tigers' pilots of the American Volunteer Group. It was given to the airmen in case they were shot down, in hopes the Chinese people would come to the pilot's aid. The Blood Chits bore the Chinese Nationalist flag, the seal (chop) of the Chinese Air Force, and Chinese lettering that read:

"This foreign person has come to China to help in the war effort. Soldiers and civilians, one and all, should rescue, protect and provide him with medical care." The message implied that a debt was owed to anyone who helped an airman avoid Japanese capture.