The Battle of the Boyne (Irish: Cath na Bóinne IPA: [ˈkah n̪ˠə ˈbˠoːn̠ʲə]) took place in 1690 between the forces of the deposed King James II, and those of King William III who, with his wife Queen Mary II (his cousin and James's daughter), had acceded to the Crowns of England and Scotland in 1689. The battle was fought across the River Boyne close to the town of Drogheda in the Kingdom of Ireland, modern-day Republic of Ireland, and resulted in a victory for William. This turned the tide in James's failed attempt to regain the British crown and ultimately aided in ensuring the continued Protestant ascendancy in Ireland.

The battle took place on 1 July 1690 O.S. William's forces defeated James's army, which consisted mostly of raw recruits. Although the Williamite War in Ireland continued until the signing of the Treaty of Limerick in October 1691, James fled to France after the Boyne, never to return.

Background

The battle was a major encounter in James's attempt to regain the thrones of England and Scotland, resulting from the Invitation to William and William's wife, Mary, from the 'immortal seven' English peers to take the throne to defend Protestantism. But the conflict had broader and deeper European geopolitical roots, of the League of Augsburg and the Grand Alliance against the expansionist ambitions of Catholic Louis XIV of France, or of the House of Bourbon against the House of Habsburg. If the battle is seen as part of the War of the Grand Alliance, Pope Alexander VIII was an ally of William and an enemy to James; the Papal States were part of the Grand Alliance with a shared hostility to the Catholic Louis XIV of France, who at the time was attempting to establish dominance in Europe and to whom James was an ally.

The previous year William had sent the Duke of Schomberg to take charge of the Irish campaign. He was a 75-year-old professional soldier who had accompanied William during the Glorious Revolution.