The Boxer Rebellion occurred when a conservative nationalist government took power in China in 1898 and prompted the Boxers, a secret society with anti-Christian sentiments, to rebel against the presence of Westerners in the country. The Boxers were generally anti-foreigner but focused particularly on Chinese Christians and Christian missionaries.
The Boxers (Yihequan or "Righteous and Harmonious Fists") were a secret society that got their name from practicing boxing rituals that they believed made them impervious to weapons. By 1898, they had a significant presence in the northern provinces of China. In that same year, the empress dowager Cixi staged a military coup in response to plans by the emperor to strongly westernize China's economy and educational system. The new conservative government legitimized the Boxers by naming them as local militias in the Shangdong province and giving them some measure of official power.
Over the next two years the Boxers openly attacked missionaries and Chinese Christians with the tacit approval of the government. An international relief force attempted to enter Beijing in response to this in 1900. Imperial forces turned this force away while the Boxers killed Christians and burned churches and foreign residences in the city. The international relief force then took forts on the coast by force to gain access to Beijing, prompting Cixi to order all foreigners killed. The rebellion ended when Beijing was captured by international forces in August of 1900.