At midday on April 18, 1942, 16 U.S. Army bombers, under the command of daredevil pilot Lt. Col. Jimmy Doolittle,
thundered into the skies over Tokyo and other key Japanese industrial cities in a surprise raid designed to
avenge the attack on Pearl Harbor. For the 80 volunteer raiders, who lifted off that morning from the carrier Hornet,
the mission was one-way. After attacking Japan, most of the aircrews flew on to Free China, where low on fuel,
the men either bailed out or crash-landed along the coast and were rescued by local villagers, guerrillas and missionaries.

That generosity shown by the Chinese would trigger a horrific retaliation by the Japanese that claimed
an estimated quarter-million lives and would prompt comparisons to the 1937-38 Rape of Nanking.
American military authorities, cognizant that a raid on Tokyo would result in a vicious counterattack upon free China,
saw the mission through regardless, even keeping the operation a secret from their Pacific theater allies.

http://www.smithsonianmag.com/history/untold-story-vengeful-japanese-attack-doolittle-raid-180955001/#BvfCUbMewGXPeu65.99