Since they were first excavated in 1983, the early Han dynasty texts discovered in Tomb M247 at Zhangjiashan have been the subject of much scholarly research. This paper focuses on the Gai Lu, the only military text excavated at this site, and one that continues to pose many problems. Although the manuscript of the Gai Lu appears to have been written at the very beginning of the Western Han dynasty, the text is highly corrupt and is likely to have gone through many recensions prior to being buried in this tomb. The antiquity of this text is entirely consistent with its status as an early example of a yin-yang military text, an important branch of strategic thought in early China which is recorded in the “Yiwen zhi” chapter of the Han shu, but which is now survives only through archaeological material. These have allowed scholars to interpret transmitted military texts in an entirely new light. The Gai Lu represents an extremely important example of such a yin-yang text, and also forms part of a major early Chinese literary genre: writings connected with the conflict between the kingdoms of Wu and Yue.