At the end of the Spring and Autumn Period, Wu and Qi were both maritime powers. Wu's territory is equivalent to most of Jiangsu Province today, covering northern Anhui, southern Anhui and western Zhejiang, bordering the sea in the east, Taihu Lake in the south, the border between Jiangsu and Anhui in the west and Xu Hai in the north. It is a maritime power in the south of the Yangtze River, famous for its navy. "One day can't be used by one ship", and it has a powerful navy, that is, boatmen. Relying on powerful boatmen, Wu galloped in rivers, lakes and seas, and frequently engaged in water wars for hegemony. Qi is a powerful country in the East. Its territory has Mount Tai in the south, Bohai Sea in the north, Qinghe River in the west and the sea in the east. At the end of the Spring and Autumn Period, the State of Qi had a strong boatman. In 486 BC, after Fu Cha, the king of Wu, broke the state of Yue, he was determined to compete with Qi in the north, so he dug through the Han ditch between the Yangtze River and Taihu Lake and the Huaihe River, so as to lead troops to attack. In 485 BC, Wu joined forces with Lu, Yong, Yong and other countries to attack Qi, and sent doctors to command shipmen to "enter Qi from the sea". Qi immediately sent a boat division to intercept it. The two countries fought a large-scale naval battle in the Yellow Sea. In the end, the Qi navy defeated the Wu navy and forced the Wu navy to return.