The Battle of the Boyne (Irish: Cath na Bóinne, IPA: [ˈkah n̪ˠə ˈbˠoːn̪ʲə]) was fought in 1690 between two rival claimants of the English, Scottish, and Irish thrones – the Catholic King James and the Protestant King William (who had deposed James in 1688) – across the River Boyne near Drogheda on the east coast of Ireland. The battle, won by William, was a turning point in James' unsuccessful attempt to regain the crown and ultimately helped ensure the continuation of Protestant supremacy in Ireland. Ironically, some contemporary historians have speculated that William's campaign may have been funded, at least in part, by Pope Alexander VIII as part of a shared hostility with William to Louis XIV of France, who at the time was attempting to establish dominance in Europe and to whom James was an ally.^[1]

The battle took place on 1 July 1690 in the "old style" (Julian) calendar. This was equivalent to 11 July in the "new style" (Gregorian) calendar, although today its commemoration is held on 12 July.^[2] William's forces defeated James' army of mostly raw recruits. The symbolic importance of this battle has made it one of the best-known battles in British–Irish history and it is a key part of the folklore for the Orange Order. Its commemoration today is principally by the Orange Institution.