A modern cavalry expert traveled through the Warring States Period and took charge of the remnants of hundreds of cavalry. With military intuition and innovative ideas that transcended the times, he set off an iron-blooded storm in the Qin State, which relied heavily on infantry and lightly cavalry.
From improving stirrups and innovating tactics to creating the world-famous "Tiger Roaring Camp", he crushed the defense lines of the six countries with his iron hoofs and attacked the Huns from the north to seal the wolf in Xu.
This is a dimensionality reduction strike in the cold weapon era. One man and one cavalry reshape the laws of war. They eventually become servants of the empire and are granted the title of Marquis of Che, and the cavalry hegemony is deeply rooted in the mountains and rivers of the Qin Dynasty.