The one where the most people died.
The Japanese attack on the US Fleet at Pearl Harbor.
It could also be known as the 'Bombing of Pearl Harbor' of the 'Start of World War II'.
Bombing of Ulm in World War II happened in 1944.
Bombing of Königsberg in World War II happened in 1944.
Bombing of Lübeck in World War II happened in 1942.
Bombing of Bangkok in World War II happened in 1944.
Bombing of Stuttgart in World War II happened in 1943.
Bombing of Braunschweig in World War II happened in 1944.
Bombing of Pforzheim in World War II happened in 1945.
Bombing of Darmstadt in World War II happened in 1944.
Yes, although some Americans apparently don't accept that it was a "World" War until USA joined in, which was immediately AFTER Pearl Harbor attack.