The Twelfth (also called the Glorious Twelfth) is a Protestant celebration held on 12 July. It began during the late 18th century in Ulster. It celebrates the Glorious Revolution (1688) and victory of Protestant king William of Orange over Catholic king James II at the Battle of the Boyne (1690), which began the Protestant Ascendancy in Ireland. On and around the Twelfth, large parades are held by the Orange Order and Ulster loyalist marching bands, streets are bedecked with British flags and bunting, and large towering bonfires are lit.
The Twelfth itself originated as a celebration of the Battle of Aughrim, which took place on 12 July 1691 in the Julian calendar then in use. Aughrim was the decisive battle of the Williamite war, in which the predominantly Irish Catholic Jacobite army was destroyed and the remainder capitulated at Limerick. The Twelfth in the early 18th century was a popular commemoration of this battle, featuring bonfires and parades. The Battle of the Boyne (fought on 1 July 1690) was commemorated with smaller parades on 1 July. However, the two events were combined in the late 18th century.