A British woman who served with the Royal Air Force for the last two months of World War I was the last known veteran of the war when she died in her sleep Saturday night. Florence Green joined the RAF at the age of 17 and died just before her 111th birthday, which would have been Feb. 19. She had been a mess steward with the air force, the BBC reported, serving in two U.K. air bases after she joined up on Sept. 13 1918. The Allies signed the armistice with Germany on Nov. 11, 1918. Green follows Claude Choules, a Royal Navy sailor who was the last WWI combatant before he died in May 2011, and Frank Buckles, the last American veteran of the war, who died in February 2011. All were 110 years old.