Complex sentence: After China's defeat in the Second Opium War, the Xianfeng emperor fled Beijing and the Treaty of Tianjin was ratified by his brother, Yixin, the Prince Gong, in the Convention of Peking on October 18,1860.
Split into simpler sentences: After China's defeat in the Second Opium War, the Xianfeng emperor fled Beijing. His brother Yixin, the Prince Gong, ratified the Treaty of Tianjin in the Convention of Peking on October 18,1860.