I‘m in Belgrade at the moment, digging through some old photos that my grandfather, Radomir Milivojevich (1900-1973), took of the Allied Bombing of Belgrade in 1944.
This is what WIKIPEDIA says about it:
Belgrade was bombed by Anglo-American air forces on April 16 and 17, 1944, which was Orthodox Easter Day. The most important unit that took part was American 15th Air Force, based in Foggia in the south of Italy. This carpet bombing raid was executed by 600 bombers flying at high altitude. Civilian casualties were 1,160, while German military losses were 18.
Bombing of the city was repeated on April 21, April 24, May 18, June 6, July 8, and September 3, 1944.