When the Anglo-French forces invaded Beijing in 1860, Emperor Xianfeng (r. 1851-1861) of the Qing Dynasty (1644-1911) fled to Chengde (Rehe), Hebei province. At that time, Yixin received an order promoting him to Prince Kung. He negotiated with the Anglo-French forces and signed the Convention of Peking.
Then, the Qing government set up the Zongli Yamen to deal with diplomatic issues with various countries. In the process of dealing with foreign affairs, Yixin met many foreigners and launched a westernization policy, becoming a leader of the Self-Strengthening Movement.
After Emperor Xianfeng died in Rehe, Yixin and Empress Dowager Cixi conspired to launch the Xinyou Coup, also known as the Beijing Coup. Because of his meritorious performance in the coup, Yi was awarded the title of Prince of Political Deliberation, and enabled to integrate military, political, diplomatic and royal affairs, which was unique in the history of the Qing Dynasty.
Yixin first reported to the Empress Dowager to appoint Junwang (second-rank prince) as the minister according to the ancestral family law, which improved his prestige and status among the royal Manchu clans. He reorganized and controlled the Junji Chu (Grand Council), and used Han ministers Zeng Guofan, Zuo Zongtang, Li Hongzhang and others to maintain peace between the Qing government and foreign countries and to maintain the rule of the Qing Dynasty.
Empress Dowager Cixi was deeply afraid that Yixin's growing power would threaten her ruling position. In addition to trying to draw him in, she made excuses to remove Yixin from all his posts and Yixin had been back at home for 10 years. When in the 20th year of Emperor Guangxu (1894) Japan invaded Korea, Yixin was hired again to be in charge of internal and foreign affairs.
Yixin was depressed in his later years and only longed for a peaceful life. He finally moved to Jietai Temple in Mentougou, a suburb of Beijing.