Allied bombing of Yugoslavia in World War II
The Allied bombing of Yugoslavia in World War II involved air attacks on cities and towns in the Kingdom of Yugoslavia by the United States Army Air Force (USAAF) and Royal Air Force (RAF), including the Balkan Air Force (BAF), between 1941 and 1945, during which period the entire country was occupied by the Axis powers. Dozens of Yugoslav cities and towns were bombed, many repeatedly. These attacks included intensive air support for partisan operations in May-June 1944, and a bombing campaign against transport infrastructure in September 1944 as the German Wehrmacht withdrew from the Balkans. This latter operation was known as Operation Ratweek. Some of the attacks caused significant civilian casualties.
Belgrade was bombed by British and American air forces on April 16 and 17, 1944, which was Orthodox Easter Day. The most important unit that took part was the American 15th Air Force, based in Foggia in the south of Italy. This carpet bombing raid was executed by 600 aircraft flying at high altitude. Civilian casualties were as many as 1,160, while German military losses were 18. Belgrade was bombed again on 6 and 8 September 1944 with about 120 Flying Fortresses, also from the US 15th Air Force, which were accompanied by fighter planes. One unexploded bomb had a written 'Happy Easter' on the casing, which amazed citizens of Belgrade. 
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