There were battles before that one in China, but the one you’re referring to is the one that led to the rape of Nanking, and this is politically sensitive I suppose, it was a protracted campaign where the Japanese were outnumbered yet succeeded against the Chinese nationalist forces, with very little quarter being given on either side which characterized most of the fighting in China between the Japanese and the Chinese, and between the reformed government of China troops which were politically aligned with Japanese, and of course the Chinese communists who were fighting both the nationalists the Japanese and the RGC troops.
It’s very interesting period in history.
I would very much like to see Chinese troops in the game, but I personally feel that the best theater for this would be Burma, largely because some of the best Chinese nationalist formations were sent there along with some of their tanks to help the British and commonwealth forces fight the Japanese during their invasion, and of course later on when they came back to push The Japanese out, ideally the 1942 timeframe would probably be the best one to model, as it would be easier to balance and it would provide for many levels and lots of interesting weapons not to mention a very interesting map with varied terrain