Exactly how long was Shanghai Occupied by the Japanese?

Answer 1

The occupation began with the Battle for Shanghai August 13, 1937 - November 26, 1937: you would use November 26 as the start date of the occupation.

The Japanese forces in China surrendered September 9, 1945. That is the date you would use for the official end of the occupation.

Obviously, most of Shanghai was occupied prior to November 26, 1937 and the Japanese forces didn't withdraw from the area exactly on September 9, 1945, but those are the best dates we have.

Answer 2

Around 1894-95 Japan became an influential foreign power in Shanghai and built the first factories there.

The ultimate occupation following defeat of the Nationalist forces was in 1937 and lasted until the Japanese Surrender in 1945.

Capture of Shanghai was significant as it was the Financial center of China.