The burning of the Yuanmingyuan took place on September 18, 1860, when the British and French invasion forces captured Tongzhou.
On the 21st, a fierce battle between the Qing and the British and French allied forces took place at the Bali Bridge, with the commander-in-chief Sin Greenqin and others fleeing first, and the Qing army was wiped out.
The Emperor Xianfeng and others fled from the capital with the Empress and the Princess Yi on a northern hunting trip on September 22nd and fled to the summer residence of Jehol.
The allied forces attacked the capital from the Anding Gate on October 13th, and the allied forces entered Beijing from the Anding Gate.
The allied forces found that the Qing army had mistreated the British and French envoys to death, so they decided to retaliate for China's barbaric behavior and to teach the Qing royal family not to defy Britain and France in the future.
On October 18th, the British and French allied forces took over Beijing, looted and burned down the Yuanmingyuan (Garden of Perfect Brightness), which had been destroyed by the British and French. British and French forces in the suburbs of Beijing looting and burning nearly 50 days, the suburbs of the Royal Garden such as the Yuanmingyuan, Qingyi Garden, Jingmingyuan (Yuquan Mountain), Jingyi Garden (Fragrant Hills), Changchunyuan and so on have been burned to the ground.
The Qing court sent Yixin as minister plenipotentiary to negotiate peace and signed the Treaty of Beijing between Britain and France. The allied forces ransacked and burned the Yuanmingyuan and Jingyi Garden. The Yuanmingyuan fire lasted three days and three nights, and more than 300 eunuchs and court ladies were buried in the flames. The French writer Victor Hugo strongly condemned it, calling it "the victory of two bandits".
Expanded Information
In May 1858, the British and French allied forces invaded the Dagu Fortress and threatened to attack Beijing, forcing the Qing government to sign the Treaty of Tianjin on June 23rd with the United Kingdom, France, Russia and the United States.
The main contents: ministers were stationed in Beijing; Niuzhuang, Dengzhou, Tainan, Danshui, Chaozhou, Qiongzhou, Hankou, Jiujiang, Nanjing and Zhenjiang were opened as ports of commerce; foreign merchant ships were allowed to sail freely into the ports of commerce along the Yangtze River; foreigners were allowed to travel and do business in the interior; foreign missionaries were allowed to go to the interior to preach freely; and China compensated the British and the French with 6,000,000 taels of silver.
In October 1860, the British and French invasion forces occupied Beijing. The invaders threatened to burn down the Imperial Palace, forcing the Qing government to sign the Sino-British, Sino-French, and Sino-Russian Treaty of Beijing as a supplement to the Treaty of Tianjin, which was renewed with provisions including the opening of Tianjin as a commercial port.
Cutting off the Jiulongsi area to Britain; permitting foreigners to buy and sell people in China; returning confiscated Catholic church property, so that French missionaries could rent and buy fields and build churches at will in the provinces; and increasing the indemnity to Britain and France to 8 million taels of silver each.
Baidu Encyclopedia - The Burning of the Yuanmingyuan