Emperor Wu Dadi 吳大帝 (r. 222-252), personal name Sun Quan 孫權 (182-252), courtesy name Zhongmou 仲謀, was the founder of the Wu dynasty 吳 (222-280) that ruled over of the Three Empires 三國 (220-280). He was the younger brother of Sun Ce 孫策 (175-200) and son of Sun Jian 孫堅 (155-191), a warlord in the last decade of the Later Han period 後漢 (25-220).
Sun Quan hailed from Fuchun 富春 (modern Fuyang 富陽, Jiangsu) and took part in his brother's conquest of the lower Yangtze region. When Sun Ce died in 200, Sun Quan took over his troops and his administrative apparatus. Sun Quan was able to attract a lot of capable political advisors, like Zhou Yu 周瑜 (175-210), Zhang Zhao 張昭 (156-236), Cheng Pu 稱普, Lu Su 魯肅 (172-217) and Zhuge Jin 諸葛瑾 (174-241).
In 208, when the powerful warlord of the north, Cao Cao 曹操 (155-220), threatened to conquer the middle Yangtze valley, Sun Quan was so frightened that he thought about offering his submission, yet Zhou Yu and Cheng Pu suggested creating an alliance with Liu Bei 劉備 (161-222), who controlled the region of Shu 蜀 in the Sichuan Basin. The united army was able to defeat Cao Cao's troops in the battle of the Red Cliff (Chibi 赤壁, modern Puqi 蒲圻, Hubei), with the outcome that none of the three warlords was able to conquer the territory of the other. Consequently, the Three Kingdoms developed.
When Cao Cao's son Cao Pi 曹丕 (187-226) proclaimed the Wei dynasty 魏 (220-265) in 220, Sun Quan officially accepted him as the new sovereign, and was rewarded for this step with the title of Prince of Wu 吳王. In 222 Sun Quan, his territory solidified enough, proclaimed himself Emperor of Wu, with the capital Wuchang 武昌 (modern Echeng 鄂城, Hubei). He choose a reign motto, established his own court and later moved the capital to Jianye 建業 (modern Nanjing 南京, Jiangsu). Sun Quan expanded his territory to the south, pacified the natives tribes in the hills of Fujian and Hunan, and advanced to the South China Sea.
Sun Quan's alliance with Liu Bei continued, yet the armies of Wu conquered the middle Yangtze region, a war during which general Guan Yu 關羽 was killed. In the battle of Yiling 夷陵, Sun Quan defeated the troops of Liu Bei and pressed him back into the Sichuan Basin. Yet in order to check the expansion of the empire of Wei, the Sun Quan and Liu Bei made peace again.
Sun Quan's political surviving depended to a large extent from the cooperation with the local gentry of the lower Yangtze region, so that he had to include members of the eminent families in his administration and granted them large tracts of lands that had been conquered in the hill regions. The montain tribes (shanyue 山越) were forced to cede their lands that were settled by Chinese immigrants. The economical sourced with which the southern gentry was endowed also gave them a lot of political influence that the Wu dynasty had always to respect. This circumstance as well as the differences between different groups at the court endangered the dynasty. In his later years, Sun Quan demoted his crown prince Sun He 孫和 and killed the Prince of Lu 魯王, Sun Ba 孫霸, and nominated youngest son Sun Liang 孫亮 (r. 252-258 CE) as his heir.