Saint Helena
In 1815, the British government selected Saint Helena as the place of detention of Napoleon Bonaparte. He was taken to the island in October 1815. Napoleon stayed at the Briars pavilion on the grounds of the Balcombe family's home until his permanent residence, Longwood House, was completed in December 1815. Napoleon died there on 5 May 1821.

Q: The British government detained who in Saint Helena?
Napoleon Bonaparte