Were Napoleon and Napoleon III alive at the same time?
Yes. Napoleon and Napoleon III were alive at the same time for 13 years, from 1808 to 1821.
Napoleon was 38 when Napoleon III was born.
Napoleon III was 13 when Napoleon died, aged 51.
Napoleon
French military leader, French Emperor 1804–1814 and again in 1815
Born 15 August 1769 · died 5 May 1821, aged 51
Napoleon III
President of the Second French Republic, Emperor of the Second French Empire and last monarch of France
Born 20 April 1808 · died 9 January 1873, aged 64