Boxer Rebellion. China formally declares war on the United States, Britain, Germany, France and Japan, as an edict issued from the Empress Dowager Cixi.

Empress Dowager Cixi (Chinese: ; pinyin: Cx Tihu [ts. t.x]; Manchu: Tsysi taiheo; formerly romanised as Empress Dowager T'zu-hsi; 29 November 1835 15 November 1908), of the Manchu Yehe Nara clan, was a Chinese noblewoman, concubine and later regent who effectively controlled the Chinese government in the late Qing dynasty for 47 years, from 1861 until her death in 1908. Selected as a concubine of the Xianfeng Emperor in her adolescence, she gave birth to a son, Zaichun, in 1856. After the Xianfeng Emperor's death in 1861, the young boy became the Tongzhi Emperor, and she assumed the role of co-empress dowager, alongside the Emperor's widow, Empress Dowager Ci'an. Cixi ousted a group of regents appointed by the late emperor and assumed the regency along with Ci'an, who later died under mysterious circumstances. Cixi then consolidated control over the dynasty when she installed her nephew as the Guangxu Emperor at the death of her son, the Tongzhi Emperor, in 1875. This was contrary to the traditional rules of succession of the Qing dynasty that had ruled China since 1644.

Cixi supervised the Tongzhi Restoration, a series of moderate reforms that helped the regime survive until 1911. Although Cixi refused to adopt Western models of government, she supported technological and military reforms and the Self-Strengthening Movement. She supported the principles of the Hundred Days' Reforms of 1898, but feared that sudden implementation, without bureaucratic support, would be disruptive and that the Japanese and other foreign powers would take advantage of any weakness. She placed the Guangxu Emperor, who, she thought, had tried to assassinate her, under virtual house arrest for supporting radical reformers, publicly executing the main reformers. After the Boxer Rebellion led to invasion by Allied armies, Cixi initially backed the Boxer groups and declared war on the invaders. The ensuing defeat was a stunning humiliation. When Cixi returned to Beijing from Xi'an, where she had taken the emperor, she became friendly to foreigners in the capital and began to implement fiscal and institutional reforms aimed to turn China into a constitutional monarchy. The deaths of both Cixi and the Guangxu Emperor in November 1908 left the court in hands of Manchu conservatives, a child, Puyi, on the throne, and a restless, deeply divided society.

Historians both in China and abroad have debated her legacy. Conventionally denounced as a ruthless despot whose reactionary policies although successfully self-serving in prolonging the ailing Qing dynasty led to its humiliation and utter downfall in the Wuchang Uprising. Revisionists suggested that Nationalist and Communist revolutionaries scapegoated her for deep-rooted problems beyond salvage, and lauded her maintenance of political order. She was responsible for numerous effective, if belated reforms including the abolition of slavery, ancient torturous punishments and the ancient examination system in her ailing years. The latter was supplanted by institutions including the new Peking University.

The Boxer Rebellion, the Boxer Uprising, the Boxer Insurrection, or the Yihetuan Movement was an anti-foreign, anti-colonial, and anti-Christian uprising in China between 1899 and 1901, towards the end of the Qing dynasty, by the Militia United in Righteousness (Yìhéquán), known as the Boxers in English because many of its members had practised Chinese martial arts, which at the time were referred to as Chinese Boxing.

After the Sino-Japanese War of 1895 villagers in North China feared the expansion of foreign spheres of influence and resented the extension of privileges to Christian missionaries, who used them to shield their followers. In 1898 Northern China experienced several natural disasters, including the Yellow River flooding and droughts, which Boxers blamed on foreign and Christian influence. Beginning in 1899, Boxers spread violence across Shandong and the North China Plain, destroying foreign property such as railroads and attacking or murdering Christian missionaries and Chinese Christians. The events came to a head in June 1900 when Boxer fighters, convinced they were invulnerable to foreign weapons, converged on Beijing with the slogan "Support the Qing government and exterminate the foreigners." Diplomats, missionaries, soldiers and some Chinese Christians took refuge in the diplomatic Legation Quarter. An Eight Nation Alliance of American, Austro-Hungarian, British, French, German, Italian, Japanese and Russian troops moved into China to lift the siege and on June 17 stormed the Dagu Fort, at Tianjin. The Empress Dowager Cixi, who had initially been hesitant, now supported the Boxers and on June 21, issued an Imperial Decree declaring war on the invading powers. Chinese officialdom was split between those supporting the Boxers and those favouring conciliation, led by Prince Qing. The supreme commander of the Chinese forces, the Manchu General Ronglu (Junglu), later claimed he acted to protect the foreigners. Officials in the southern provinces ignored the imperial order to fight against foreigners.

The Eight-Nation Alliance, after initially being turned back by the Imperial Chinese military and Boxer militia, brought 20,000 armed troops to China. They defeated the Imperial Army in Tianjin and arrived in Beijing on August 14, relieving the fifty-five day siege of the Legations. Plunder of the capital and the surrounding countryside ensued, along with summary execution of those suspected of being Boxers in retribution. The Boxer Protocol of September 7, 1901, provided for the execution of government officials who had supported the Boxers, provisions for foreign troops to be stationed in Beijing, and 450 million taels of silver— more than the government's annual tax revenue—to be paid as indemnity over the course of the next 39 years to the eight nations involved. The Qing dynasty's handling of the Boxer Rebellion further weakened their control over China, and led the dynasty to attempt major governmental reforms in the aftermath.