The Williamite War in Ireland was a war fought between the Protestant supporters of King William III of England (the "Williamites") and the Anglo-Irish Catholic supporters of the deposed King James II of England (the "Jacobites") in Ireland from 1689 to 1691, in the aftermath of the Glorious Revolution.
James II had been deposed by his nephew William of Orange and his daughter Mary in November 1688 following the birth of a Catholic heir to the throne, James Francis Edward Stuart, and the Catholic King James' attacks on the Church of England. In March 1689, James landed at Kinsale in Ireland, 75% of whose population was Catholic, and where Richard Talbot, Earl of Tyrconnell had assembled a large Catholic army of 36,000 levies in support of James' restoration. James brought French weapons and trainers to this poorly-organized army, and he won Catholic support through reversing the 17th century confiscations of Catholic lands and granting autonomy to the Parliament of Ireland. These moves angered Ulster Protestants, who made up 50% of the population in that region, thus providing the new King William with a base of support in Northern Ireland.
William viewed James' landing in Ireland as a French proxy invasion, and Parliament approved funding for a 22,230-strong expeditionary force of English soldiers and European mercenaries to restore order to Ireland. While the Jacobites besieged Derry, the Williamites moved to secure Ireland's eastern coast to prevent the Jacobites from reinforcing the rebellion in Scotland, and, over the course of one week in July, the Williamites recaptured Ulster and captured Carrickfergus on 27 August. James was hampered by the Irish Parliament's hesitancy to fight the Williamites, as they preferred to negotiate a compromise with William rather than risk their armies and finances in pitched battles. James' strategy was instead to prolong the war, as his French backers sought to divert British military attention away from the War of the Grand Alliance on the European continent by encouraging peripheral rebellions in Ireland and Scotland. This strategy devastated the civilian population, as prolonged conflict brought about starvation as soldiers requisitioned the civilian populace's food and supplies for themselves.
In April 1690, 6,000 French regulars in Ireland arrived, trading places with 5,387 Irish veterans, who were sent to the continent to serve in the French Royal Army. In June 1690, 31,000 Dutch, English, and Danish soldiers were shipped to Belfast on 300 ships, providing William with his own reinforcements. These two armies met at the Battle of the Boyne near Drogheda on 1 July 1690, and, while the fighting was inconclusive, the Jacobites were forced to abandon Dublin to the Williamites. That same day, however, a French naval victory at the Battle of Beachy Head caused invasion fears in England, fears which abated after the French failed to make use of the victory before the Anglo-Dutch fleet could reestablish control over the English Channel. On 17 July, William's Declaration of Finglas excluded Jacobite officers and the Catholic landed class from a pardon, encouraging them to keep fighting. William's army was defeated in its siege of Athlone, and, while John Churchill captured Cork for William, Limerick repulsed several Williamite assaults with heavy losses. In late 1690, William left Ireland to focus on the war in Europe, allowing the Jacobites to retain large parts of western Ireland.
The Dutch general Godert de Ginkel assumed command of the Williamite forces, while James Douglas held command in Ulster and Ferdinand Willem of Wurttemberg-Neuenstadt commanded the Danish forces at Waterford. By 24 July 1690, James all but accepted defeat and allowed the French brigade and any willing Irish officers to evacuate to the continent. The king's son James FitzJames, 1st Duke of Berwick was left in command of the Jacobite forces in Ireland after Tyrconnell left for France, but he was forced to deal with growing divisions between Tyrconnell's pro-negotiation camp and Patrick Sarsfield's pro-war, Irish nationalist faction. King Louis XIV dispatched Charles Chalmot de Saint-Ruhe with French food and arms to aid the flagging Jacobite cause, arriving at Limerick on 9 May 1691. However, the French brought no reinforcements, and Athlone fell to the Williamites on 30 June. On 12 July, at the Battle of Aughrim, the Jacobite army was shattered and Saint-Ruhe killed, and Limerick fell to the Williamites in October. On 3 October 1691, Sarsfield signed the Treaty of Limerick, which guaranteed Catholic religious freedoms and legal protections to any Irish Jacobites who would swear allegiance to King William and Queen Mary. Those still serving in the Jacobite army were allowed to emigrate to France, and 19,000 Irish "Wild Geese" did so. Parliament soon reneged on its promises to Catholics, forcing lawyers, physicians, and Irish MPs to deny transubstantiation while taking the Oath of Supremacy after 1691; the Penal Laws, in force from 1695 to 1829, disenfranchised Catholics and effectively restricted political and material power to the Anglican "Protestant Ascendancy" in Ireland. Anglo-Irish Anglicans became the new elite in Ireland, forming a third of the British Army officer class by the 1770s; both Irish Catholics and Ulster Scots Presbyterians were excluded from power, setting the stage for the Irish Rebellion of 1798 a century later.