Bombing of Warsaw 25th Sept 1939
..on 25 September, Luftwaffe bombers under the command of Major General Wolfram von Richthofen conducted the first major city attack of World War II, dropping 500 tons of high explosive bombs and 72 tons of incendiary bombs, in coordination with heavy artillery shelling by Army units. The center of Warsaw was badly damaged. Approximately 1,150 sorties were flown by a wide variety of aircraft, including even obsolescent Junkers Ju-52/3m bombers, which dropped 13 percent of the incendiary bombs dropped on the day.
http://www.richmond.edu/~wgreen/ECDwarsaw.html