Orangemen

Orangemen, a name given to an association of Protestants in Ireland instituted to uphold the Protestant succession to the crown, and the Protestant religion as settled at the Revolution of 1688, and which derives this name from William, the Prince of Orange, on whose accession to the throne Protestantism was established; it became dormant for a time after its institution, but it has shown very decided signs of life at political crises when Protestantism seemed in danger, such as often to call for some firm handling.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Orange River Colony * Oratorio
Opie, John
Opinicus
Opitz, Martin von
Oporto
Opportunist
Optimism
Opus Operatum
Oran
Orange River
Orange River Colony
Orangemen
Oratorio
Oratory, Congregation of the
Orcagna
Orchardson, William Quiller
Orcus
Ordeal
Ordericus Vitalis
Orders in Council
Oreades
Oregon