The Boxer Rebellion took place in 1900. It was initiated and led by a secret Chinese society called the Boxers, so named because members practiced forms of boxing and martial arts that they believed made them impervious to bullets.
The rebels, with the support of the Empress of China, fought the Western powers that been running China for more than half a century. The Chinese resented the arrogant attitudes and looting of their country by these foreign powers, who did not consider Asians the equal of white Europeans and did not respect Chinese culture or religion. The Boxer movement represented an expression and assertion of Chinese cultural pride as much as an attempt to expel parasitic foreign powers.
The Boxers, however, were not impervious to bullets, and the weak Chinese monarchy could not adequately support the rebels against the superior wealth and technology of the West. The defeat of the Boxers was a crushing blow to the Chinese on a cultural level, robbing them of their dignity. One long-term effect was to undermine the monarchy to such an extent that a decade later it fell, to be replaced by a Western-style republic.
The Chinese suffered greatly after the Boxer rebellion, humiliated, forced to pay reparations, and increasingly weakened and impoverished. The most important long term effect was to sow such despair in the country that many people were attracted to the message of hope offered by Mao and the Communist Party. This led to China becoming a communist state in 1949.