Battle of Lake Poyang

The naval battle of Lake Poyang (鄱陽湖之戰) took place 30 August – 4 October 1363 CE and was one of the final battles fought in the fall of China's Mongol-led Yuan Dynasty. There were at this time a number of rebel groups who sought to topple the reigning dynasty; the three most powerful were the Ming, the Han, and the Wu.

The navy of the Ming, under Zhu Yuanzhang, met the Han navy, commanded by Chen Youliang, in Jiangxi Province on Lake Poyang, China's largest freshwater lake.

Background
The battle of Lake Poyang began as an amphibious siege by the Han against the Ming-held town of Nanchang. The descriptions from the time seem to indicate the use of lóu chuán (楼船, tower ships), which were essentially floating fortresses, very tall and strong, but also relatively slow, and requiring deep water to sail.

Nanchang defended itself well against the siege, the city's tall walls rendering the chief strength of the tower ships to no advantage; the ground assault was repelled as well for some time. A Ming messenger managed to break through the Han fleet's blockade, getting out a call for help to Zhu Yuanzhang. The majority of the Ming forces, in particular its ships, were occupied at the time in fighting Zhang Shicheng's Wu Kingdom elsewhere, but Zhu nevertheless arrived with what force he could muster. These ships were, on average, smaller than the Han ships, which meant a disadvantage in size and strength, but also great advantages in speed, maneuverability, and viability in shallow waters. The summer sun had already caused the lake's water level to drop considerably, to the Ming's advantage. They sailed for nine days from Zhu's capital Nanjing to Nanchang, capturing the town of Hukuo along the way on 25 August.

By the time the Ming fleet arrived, Chen Youliang, the Han commander, realised that Nanchang was not going to surrender soon, and so he redirected his focus on defeating the arriving Ming fleet. Knowing that his own fleet was suited more for siege than for naval combat, he hoped to finish the battle quickly, before the water levels sank any further.

The battle
The Ming fleet divided itself into eleven squadrons, with the heavier ships at the centre; a number of their warriors disembarked to bolster the Nanchang garrison. Following the Ming arrival, both fleets dropped anchor for the night. The fighting commenced the following morning, on 30 August.

The core of the Ming fleet made a frontal assault on the Han ships, while some of the other squadrons moved to positions from which they could launch trebuchets, fire ships, and other explosives and the like. Though they managed to set more than twenty Han ships alight, their own flagship was set aflame by the Han. Zhu Yuanzhang rushed to extinguish the flames as the Han fleet concentrated all their attacks on his ship; the situation quickly grew worse for Zhu as the ship hit a sandbar and stuck. The Han circled around and continued to attack with arrows and flame. However, the Ming fleet quickly came to the rescue of their commander, the waves created by their very movement shaking the flagship free.

The lighter, smaller Ming ships became grounded several times more during the battle, due to their attempts to encircle the Han ships and to board their enemies' ships; the Han intentionally kept to the deeper waters and made no attempts of boarding attacks.

That night the Ming ships were sent downstream a short way for repairs and regrouping. Zhu's plan had failed, but the battle was not over yet. The following day, the Ming discovered that the Han had rearranged their fleet into a solid line of heavy tower ships, with their smaller ships skirting the edges of the formation; their ships were tied together by chains.

The main action of that day (31 August) involved the creation and launching of fire ships by the Ming. Small rafts and fishing boats were loaded up with bales of straw and gunpowder, set aflame, and launched toward the enemy fleet. Dummies with armour and weapons were placed on the fireships as well, to aid in confusing and tricking the enemy. Due to a favourable wind, and the tight formation of the Han fleet, the fire ships were very successful, and many Han ships were either destroyed or suffered extensive damage.

After spending more than a full day repairing their ships, both fleets returned to battle two days later on 2 September. Seeing the consequences of a tight formation, Chen Youliang tried a more open formation. But this only allowed the Ming to execute their originally-intended grappling and boarding attacks.

News came to Zhu Yuanzhang around this time that his ground forces had relieved Nanchang from the siege. The Ming fleet began to retreat to the mouths of the Yangtze and Gan Rivers, their defeat of the Han being all but complete. However, rather than retreating entirely, the Ming fleet remained for a month, blockading and watching the Han fleet. Neither commander wanted a war of attrition, and so there was little or no combat action for a month.

On 4 October the final elements of the battle played out. The Ming employed fire ships once again, and at one point in the conflict Chen Youliang suffered an arrow through his skull and died. The Han surrendered shortly afterwards.

Aftermath
Chen Youliang was succeeded by his son, Chen Li, who was lost to Zhu.

The Ming victory here cemented their position as the leading rebel group, and the one that would take command when the Yuan Dynasty fell. When this happened five years later, Zhu Yuanzhang became the first Emperor of the Ming Dynasty.