Wu. In 506 BC, during the reign of King Zhao of Chu, King Helü decided to invade Chu. The king personally led the army, along with his younger brother Fugai, Wu Zixu, as well as Sun Tzu, author of The Art of War. Although Chu had a strong army led by Nang Wa and Shen Yinshu, it suffered a heavy defeat at the Battle of Boju. King Zhao of Chu fled to Sui and the Wu army captured Ying, Chu's capital. After entering Ying, Wu Zixu exhumed King Ping's corpse, and gave it 300 lashes to exact vengeance on for his mother and brother who were murdered by the Chu King. The military victory led to Wu Zixu's elevation to Duke of Shen and his alias Shenxu. After these victories, Wu was briefly the most powerful nation and turned to other campaigns, defeating the State of Qi in 484 BC. King Helü of Wu is considered to be one of the Five Hegemons of China during the Spring and Autumn period due to his military successes at this time with the help of his famous commander/strategist Sun Tzu. Wu is also generally regarded as developing the first Chinese Navy. This Navy was quite complex and had different classes of ships. These "classes" of ships were the great wing (da yi), the little wing (xiao yi), the stomach striker (tu wei), the castle ship (lou chuan), and the bridge ship (qiao chuan). These were listed in the Yuejueshu (Lost Records of the State of Yue) as a written dialogue between King Helü of Wu (r. 514 BC–496 BC) and Wu Zixu (526 BC–484 BC) in which the latter stated: Nowadays in training naval forces we use the tactics of land forces for the best effect. Thus great wing ships correspond to the army's heavy chariots, little wing ships to light chariots, stomach strikers to battering rams, castle ships to mobile assault towers, and bridge ships to light cavalry. Ironically, Wu was later threatened by an upstart state to its own south, Yue; Chu then aided Yue's rise as a counter to Wu. Although Wu won majority of battles against the Yue and captured their King Goujian, Wu failed to completely subjugate Yue, in part because of Fuchai's willingness to let King Goujian live in Wu as his servant. King Goujian suffered for years as Fuchai's servant/slave and planned his revenge. Fuchai