The US Congress declares war on the German Empire, bringing the United States into World War I on the Allied side.
The Bolshevik Red Army fights the White movement and other forces after the October Revolution; the Bolsheviks emerge victorious.
Protests and mutinies in Petrograd force Tsar Nicholas II to abdicate, ending more than three centuries of Romanov rule.
The British government declares support for a 'national home for the Jewish people' in Palestine, while stating that the civil and religious rights of non-Jewish communities should not be prejudiced.
The Bolsheviks led by Lenin overthrow the Provisional Government in Petrograd (25 October in the Julian calendar then used in Russia).
Irish republicans rise in Dublin and proclaim an Irish Republic; the rebellion is put down by British forces after six days.
Britain and France secretly agree to divide the Ottoman Empire's Arab lands into post-war spheres of influence.