**The** **astonishing, never-before-told story of the greatest rescue mission of World War II—when the OSS set out to recover more than 500 airmen trapped behind enemy lines in Yugoslavia. **** “An amazing, riveting tale of unsung heroes who went above and beyond.”—James Bradley, **New York Times** bestselling author of **Flags of Our Fathers** ** During a bombing campaign over Romanian oil fields, hundreds of American airmen were shot down in Nazi-occupied Yugoslavia. Local Serbian farmers and peasants risked their own lives to give refuge to the soldiers while they waited for rescue, and in 1944, Operation Halyard was born. The risks were incredible. The starving Americans in Yugoslavia had to construct a landing strip large enough for C-47 cargo planes—without tools, without alerting the Germans, and without endangering the villagers. And the cargo planes had to make it through enemy airspace and back—without getting shot down themselves. Classified for over half a century for political reasons, the full account of this unforgettable story of loyalty, self-sacrifice, and bravery is now being told for the first time ever. *The Forgotten 500* is the gripping, behind-the-scenes look at the greatest escape of World War II.