180: Six residents of Carthage, North Africa, are executed for being Christian, the earliest recorded instance of Christianity in the region

1203: The Siege of Constantinople begins during the Fourth Crusade, as Roman Catholic Crusaders, aboard a Venetian fleet, attack the city

1762: Empress Catherine II becomes Tsarina of Russia following the murder of Tsar Peter III

1918: The Romanov royal family and several of their retainers are executed by a Bolshevik firing squad in the basement of Ipatiev House, in Yekaterinburg, Siberia

1936: Spanish generals Francisco Franco and Emilio Mola lead a right-wing uprising, starting the Spanish Civil War

1945: Leaders Harry Truman, Joseph Stalin and Winston Churchill hold their first post World War II meeting at the Potsdam Conference

2014: Malaysia Airlines Flight 17 is shot down over Eastern Ukraine by a Buk surface-to-air missile launched from pro-Russian separatist-controlled territory, killing all 283 passengers and 15 crew on board

Source: Onthisday.com