Simplify the following text for a Grade 11 native English-speaking person.
Original: During the Second Sino-Japanese War ( 1937 â `` 1945 ) , it was Generalissimo Chiang Kai-shek 's provisional capital , and the Japanese Air Force bombed it heavily .
Simplified: Chongqing was the provisional capital of the government of Chiang Kai-shek during the Second Chinese-Japanese War from 1937 to 1945 .