In 1812, the United States went to war with Great Britain. On August 24, 1814, British troops took control of the capital city and proceeded to burn the President’s House (White House) and the U.S. Capitol, which then housed the congressional library (Library of Congress) in its north wing. At the time of the British invasion, the Capitol comprised two wings connected by a wooden causeway. The British used rockets and gunpowder paste to set the Capitol ablaze. The books and the wooden floor and furniture went up in flames, and the library was lost.

Source: Library of Congress