Final answer:
The destruction of the U.S. capital and other buildings in 1812 was due to a foreign invasion by the British, representing a significant event during the War of 1812.
Step-by-step explanation:
The destruction of the capital, White House, Treasury, and Library of Congress can be attributed to a foreign invasion during the War of 1812. Specifically, this act was carried out by the British under the command of Major General Robert Ross, who attacked Washington, D.C. This event is marked as the only occasion in which the United States was invaded, leading to significant destruction of its federal buildings. Among the ruined was the Library of Congress, including Thomas Jefferson's personal collection of books, which would later become the core of the new Library in 1815. Notably, the British focused on public buildings while sparing private property, with First Lady Dolly Madison making efforts to preserve valuable items from the White House. Despite the attacks, the burned buildings' sandstone exteriors endured the fires.