Alternate history
At the beginning, he is the commander-in-chief of the former enemy, but he is not brainless.
In Chapter 2, Become the Commander among the Former Enemies
Wang Feng traveled through this military academy student to the Northern Expedition and became a lieutenant general. During the Battle of Songhu, he became the commander-in-chief of the former enemy.
Have you seen it? Be the commander-in-chief at the beginning
Not bad, you can buy it
This book needs to be hung