Battle of Poyang Lake(1363 August 30, 2008-October 4, 1363) was an important battle in the late Yuan Dynasty in China. Zhu Yuanzhang defeated and killed the powerful enemy Chen Youliang in this battle. It was also regarded as the largest water battle in the medieval world.

In September of the 17th year of Zhizheng (1357), Chen Youliang attacked and killed Ni Wenjun, claiming to be the envoy of Xuanwei, with Zou Pusheng as the Grand Master and Zhang Xianxian as the Prime Minister, and raised an army to capture various roads in Jiangxi. Welcome Xu Shouhui to move his capital to Jiangzhou (now Jiujiang, Jiangxi Province). Chen Youliang held Xu Shouhui hostage and claimed to be the King of Han. He established the capital of Jiangzhou. The country was called Han and the year was named Dayi. In the twentieth year of Zhizheng (1360), Chen Youliang attacked Zhu Yuanzhang eastward and killed Xu Shouhui on the way, making himself the emperor of the Han Dynasty. Chen broke through Zhu Yuanzhang's Yangtze River Taiping Defense Line and approached the city of Jiqing (present-day Nanjing). Chen and Zhu fought fiercely in Longwan, northwest of Jiqing City. Unfortunately, the river fell and hundreds of giant ships ran aground. Chen Youliang was defeated and fled to Jiangzhou (Jiujiang). In April of the twenty-third year of Zhizheng (1363), Chen Youliang sent troops to besiege Hongdu (now Nanchang) in Jiangxi Province. The land and water armies claimed to have 600,000 people. Chen Youliang also used amphibious warfare on both land and water. The water boats used tall but slow ships, but they besieged Hongdu and failed to conquer (The guard was Zhu Wenzheng, the nephew of Zhu Yuanzhang.) In July, Zhu Yuanzhang personally led 200,000 people to save Hongdu. Chen Youliang, who was originally a rebel army of the Yuan Army, withdrew the siege and chose his best in water warfare to face Zhu Yuanzhang in Poyang Lake, the largest freshwater lake in China.

Only nine days later, the Ming Army fleet arrived in Nanchang for rescue from Nanjing. The Ming Army fleet was divided into 11 teams, with the large fleet in the center, and the remaining small fleet carrying infantry to land in Nanchang to support the Nanchang garrison. On July 20 (August 29), the main forces of the two armies faced off on Poyang Lake. The next day (August 30), the battle began at dawn. In the first three days, the Ming Army's ships and soldiers were at a disadvantage. The Han Army's "building ships" shot high and attacked the Ming Army ships at the lower level, and Zhu Yuanzhang's ship was also shot and destroyed. He was almost captured by the Han Army. Fortunately, several ships of the Royal Guards rushed to rescue Zhu Yuanzhang.

Later, Zhu Yuanzhang adopted Guo Xing's suggestion and used fire attacks and trebuchets to burn more than 20 ships and ships of the Chen army starting on the fourth day (September 2). The Han army suffered heavy casualties, and at least 25,000 Han soldiers died in the battle. Chen Youliang's brother was killed in the battle, and Chen Youliang was even more saddened. Chen Jun was angry and killed the Ming army prisoners in front of the battle, causing the Ming army to feel that there was no way to retreat and had to fight against the water; then the situation of the Chen army began to be unfavorable: Due to the long sunshine in autumn, the water level of Poyang Lake dropped. The Han army ships were heavy but had deep and slow draft and even ran aground and dared not dock. On the other hand, the Ming army ships were small and fast and could attack quickly, and they could also dock and build a water camp for a protracted war. In late August, the Ming army conquered Nanchang, and some of the Ming army's fleets withdrew to the Ganjiang River and Yangtze River, leaving only part of the fleet to continue fighting with Chen, waiting for the Ming infantry army to come and complete the water and land siege. On August 26 (October 4), Chen's army attempted to break through and return to Wuchang. At Hukou, he was intercepted by tens of thousands of arrows from the infantry of the Ming army on the shore. Chen Youliang poked his head out of his cabin and died by the arrow. Chen's army lost another 20,000 soldiers, and the remaining 500,000 remnants scattered and fled.

Chen Youliang's son Chen Li was succeeded by the remnants of his troops and later surrendered to Zhu Yuanzhang.