Oakes, Hildebrand [1 subentry]

O'Brien, Richard [19 subentries]

Ocmulgee River [2 references]

Oconee River [1 reference]

Ogden, Schwartz, & Company (Marseilles) [1 reference]

Ohio [2 subentries]

Ohio Company [1 reference]

Ohio River [7 references + 1 subentry]

Oldenburg, duke of [See redirect]

Olmütz, Austria [2 references]

O'Mealy, Michael [1 reference]

Ommanney, John Acworth [1 reference]

Oporto, Portugal [4 references]

Oran, Algiers [2 references]

Orange, Prince of [See redirect]

Orange County, Va. [1 reference]

Orange Court House, Va. [2 references]

Orcas(U.S. ship) [1 subentry]

Order of Vasa (Sweden) [1 reference]

O'Reilly, Count Alejandro [2 references]

O'Reilly, Thomas [1 reference]

Orleans, France [1 reference]

Osgood, Samuel [1 subentry]

Oster, Martin [1 subentry]

Oswego (U.S. ship) [2 references]

Otis, Samuel A. [1 reference + 1 subentry]

Otranto, Italy [1 reference]

Otto, Louis-Guillaume, comte de Mosloy [3 references + 1 “see also” entry]

Ottoman Empire [See redirect]

Oxnard, Thomas [1 subentry]