An Irish protestant organization dedicated to the preservation of the protestant constitution and the ‘glorious and immortal memory’ of King William III, the victor of the Boyne (1690). The order was founded in Loughgall (Co. Armagh) in September 1795 by the protestant veterans of a sectarian clash, the battle of the Diamond. In the later 19th cent. the order enjoyed a revival, and was one of the foundations of popular unionism in the 1880s. Since 1905 the order has been formally connected with the Ulster Unionist Party. Its most public face is the highly organized marching season.