Why is it called the Eighth Route Army instead of the Eight Route Army?

What do you mean it's obviously the 18th Army? Go check the military history of the 8th Army yourself...

In the beginning of the reorganization, the Kuomintang gave the number of the National Revolutionary Army (NRA) called the Eighth Route Army, not the Eighteenth Route Army

After a few months, the Kuomintang unified to cancel all the NRA's "Route Army" structure, and called it the "Group Army". "

This time, the new name of the Eighth Route Army was called the 18th Group Army of the National Revolutionary Army, not the 18th Route Army

It was just that at the very beginning, people were used to calling the Eighth Route Army and didn't change it, and the 18th Group Army was also more troublesome to pronounce than the Eighth Route Army.