Ottoman Empire, 1288-1918 117
Old English, ca. 450-1100 107
Occupation, 1939-1945 19
Old High German, 750-1050 10
Old Kingdom, ca. 2686-ca. 2181 B.C. 9
Orange Revolution, 2004 8
Opium War, 1840-1842 7
Occupation, 1941-1944 5
October Crisis, 1970 3
Ordovician 3
Occupation, 1941-1945 2
October 20, 1991 1
October Revolution, 1944 1
Oka Crisis, 1990 1
Old English, approximately 450-1100 1
Oligocene 1
Otto I, 936-973 1
Overthrow of the Monarchy, 1893 1
