Apparently, the Library of Peking fared rather badly in all this. The situation on the ground had spiralled completely out of control as the uprising grew more grave, especically in light of imperial European colonial and commercial interest in China. The Brotherhood of the Harmonious Fist were labelled a secret society by the European press services (though the Brotherhood was more akin to a labor union). The group's major concern were the Westerns operating in the colony; they flatly opposed the European's political and commercial manipulation of China (imagine, if you will, WTO/FTAA protesters, except 100 years ago and more hand-to-hand combat). After the European sections of the city were put under seige by their forces, several European 'missionaries' (most likely merchants or consulars) were killed in the chaos. When news reached the navies of the Western powers, the five nations with a stake in the region (England, France, Russia, Germany and Japan) proceeded to shell the city's Library from the harbour in retaliation, completely destroying its nearly 2000 year old collection.
Source: J. M. Roberts,
The History of the World (London: Helicon, 1992)