The Warring States Period sees the proliferation of iron-working in China, iron replacing bronze as the dominant metal used in warfare.

Arms of soldiers gradually change from bronze to unified iron arms.

Dagger-axes are an extremely popular weapon in various kingdoms, especially for the Qin, who produce eighteen-foot long pikes.

Military tactics also change.

Most armies in the Warring States Period, unlike in the Spring and Autumn Period, make combined use of infantry and cavalry, and the use of chariots gradually falls into disfavor.

The nobles in China thus remain a literate rather than a warrior class from this period on, as the kingdoms compete by throwing masses of soldiers against each other.