Change the name and lose the tradition.

What do you mean it's obviously the Eighth Route Army? Check the military history of the Eighth Route Army yourself. ...

At the beginning of the adaptation, the name given by the Kuomintang was the Eighth Route Army of the National Revolutionary Army, not the Tenth Route Army.

About a few months later, the Kuomintang unified all the "middle route army" organizational system of the National Revolutionary Army and renamed it "group army"

At this time, the new name of the Eighth Route Army was the 18th Army of the National Revolutionary Army, not the Eighth Route Army.

It's just that people used to call it the Eighth Route Army at first, but they didn't change it, and 18 Army was a little more troublesome to read than the Eighth Route Army.