12 July, celebrated by Orangemen in commemoration of the victories of William III in Ireland at the Battle of the Boyne (1 July 1690) and the Battle of Aughrim (12 July 1691).
Origin
Late 19th century.
Definition of Orangeman's Day in US English:
Orangeman's Day
(also Orangemen's Day)
noun
Canadian
12 July, celebrated by Orangemen in commemoration of the victories of William III in Ireland at the Battle of the Boyne (1 July 1690) and the Battle of Aughrim (12 July 1691).