After a series of military defeats in 1812-13, Napoleon was forced to abdicate the French throne on April 6, 1814. He was exiled to the island of Elba, between Corsica and Italy, but he escaped in February 1815 and took control of France again. The Allies responded by forming a Seventh Coalition, which defeated Napoleon at the Battle of Waterloo in June 1815. Napoleon was exiled again, this time to the remote island of St. Helena in the South Atlantic Ocean, where he remained until he died on May 5, 1821, at age 51. His health began to cause concern from July 1820, and he died of cancer at age 51 on St. Helena. An autopsy was performed by Dr. Antommarchi, who declared that the death had been caused by a stomach ulcer. Napoleon was buried on May 10, 1821, in a valley close to Longwood, known as Geranium Valley, under a tombstone without any inscription, because the English refused that the name be mentioned.