Serbs saved 500+ downed U.S. airmen in WWII, the largest rescue mission behind the enemy lines. Sometimes at the cost of their villages being wiped out by the Nazis for reprisal.
How U.S. thanked Serbs? In single air raid on Belgrade (EASTER SUNDAY APRIL 16 1944) 15th USAAF killed 2000 Belgrade citizens, 4 times more than Nazis killed in Coventry, 2 times more than NAzis killed in Rotterdam, and thousands more in Nish and Pirot. Officially, navigational error. Unofficially, help to communist partisans to sieze power in Serbia.
After the war, President Truman awarded Congressional medal of Honor to Gen. Mihajlovich.