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This is going to be in basic outline form for now:

POD: 1381, a Muslim boy from Yunnan, Ma He, is not castrated by the Ming Dynasty. However, he is sent eastwards to Nanjing, the Ming Dynasty Capital, where he is adopted by a scholar-official at the Ming Imperial Court named Guo Lin(*), who sees promise in the boy and tries to prevent his castration. Guo knows that Zhu Yuanzhang, the Hongwu Emperor, resents the scholarly class and places great trust in his eunuchs and Jinyi Wei, his secret police service. However, Guo himself will bide his time and wait for the Hongwu Emperor to die, so that a more scholar-friendly emperor can be placed on the throne. Guo himself dies in 1395 of tuberculosis, which is three years before Hongwu's death. By now, the boy formerly known as Ma He has passed his civil service examinations and is working at the Imperial Court in Nanjing.

1398: Upon Hongwu's death, Zhu Yunwen, grandson of Zhu Yuanzhang, takes the throne as the Jianwen Emperor. Ma He becomes a close advisor to the young Emperor and recommends that he allow Zhu Di, his uncle, to pay tribute to the recently deceased Hongwu Emperor instead of barring him from the city of Nanjing. Zhu Di however, has designs on the throne and begins to form a rebellion movement centered around the city of Beijing. However, the Jianwen Emperor abolishes certain lesser princedoms to undermine Zhu Di's support, and replaces other princes with loyalist generals. Ma He gets a military command in the Huaihai region.

1399: In the meantime, Jiao Yu, a firearms and explosives expert, finally gets around to publishing the entirety of the Huolongjing, a manual on the construction and employment of various firearms. The work becomes widely circulated in the Chinese military establishment. An enterprising young blacksmith in Nanjing reads a copy of the manual and applies the wheel lock mechanism, previously used only for detonating landmines, to personal firearms, thus making them far more reliable than the old matchlocks. The Imperial military immediately commissioned three hundred such weapons to equip the city garrison of Nanjing with them. The technology begins to spread to other parts of China.

1400: Zhu Di and his force of rebels and mercenary Mongols begin their march south, into Ma He's military command near the Huai Hai river. Reinforcements sent by the Emperor under general Li Jinglong prove to be incompetent as Zhu Di outwits Jianwen's forces. However Ma He proves to be a more than competent commander and engages in a fighting retreat towards Nanjing, harassing Zhu Di's forces all the way while reinforcements from the south are brought up, still under the command of Li Jinglong. Ma is badly outnumbered by the rebels and lacks sufficient amounts of gunpowder and weapons.

1401: The Jianwen Emperor flees to the south as Zhu Di's forces lay siege to Nanjing. Ma He is given command of the Yangtze River naval flotilla, while Li Jinglong commands the forces in Nanjing itself. During the battle, Li Jinglong simply throws the gates of the city open and defects to Zhu Di's forces. However, Ma He excellent command of the navy outside of Nanjing means that Zhu Di is unable to force a river crossing, especially since loyalist forces still hold Suzhou. Zhu Di is forced to make camp for the winter in Nanjing. In the spring, he attempts to force a crossing of the Yangtze at Hefei, but Ma He's superior command of the navy again stymies his attempt. Imperial reinforcements from the south arrive and lay siege to Nanjing, which is nearly leveled in the house to house fighting that takes place inside the city. Loyalist forces move north into the Huaihai and Shandong regions, closing in on Zhu Di's base of Beijing. However, resistance is stiff as Li Jinglong is fighting with the sort of competence he never showed while acting in the name of the Emperor.

1402: By now, Zhu Di and his rebels have been forced into the city of Beijing, and the forces of Ma He and the Jianwen Emperor are laying siege. However, the fighting is intense, with both forces equipped with wheel lock firearms. When the city is broken into, Zhu Di commits suicide, and his rebels surrender. With the civil war over, there is peace in China. The Emperor gives Ma He the honorific name of Zheng He and command of the Admiralty. The Jianwen Emperor moves the capital of China north to Beijing to keep a closer eye on the Mongol threat. He also orders the construction of a large fleet of more than 2000 ships in order to strengthen his navy. Shipbuilding for the fleet begins at Guangzhou, Quanzhou and Hangzhou, with some of the ships being up to 100 meters in length.
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