Historical Events Aug 18 St Sixtus III ends his reign as Catholic Pope Sep 29 Pope Leo I the Great, installed Famous People Who Died in 440 AD Feb 17 St. Mesrop Mashtots, Armenian monk, theologian and linguist known for inventing the Armenian alphabet in c. 405 AD, dies (b. 361/362) Aug 18 Sixtus III, Italian Pope (432-40), dies 439 AD History by Year 444 AD