The military career of Napoleon Bonaparte spanned over 20 years. As emperor, he led the French armies in the Napoleonic Wars. Widely regarded as a military genius and one of the finest commanders in history, his wars and campaigns have been studied at military schools worldwide. He fought more than 70 battles, losing only eight, mostly at the end. In many statistical research papers Napoleon is named the most successful military leader in history. The great French dominion collapsed rapidly after the disastrous invasion of Russia in 1812. Napoleon was defeated in 1814 and exiled to the island of Elba, before returning and was finally defeated in 1815 at Waterloo. He spent his remaining days in British custody on the remote island of St. Helena.