William of Orange, who had been invited to invade England by several English nobles opposed to the Catholic King James II, arrived in Ireland in June 1690. His landing at Carrickfergus was part of a broader strategy to eliminate the rule of James II and was seen as a pivotal moment in the ongoing power struggle between Catholics and Protestants in the British Isles. Upon his arrival, William brought with him an army of roughly 25,000 troops, composed mainly of Dutch and English soldiers, in order to solidly challenge the authority of James, who was entrenched with his own army of about 22,000 Irish troops. The military confrontation that ensued was not just about the English crown, but also represented greater religious and political tensions in the region.

The Williamite War in Ireland had roots in a larger conflict, namely the Glorious Revolution, which sought to solidify Protestant control over England and its colonies. William's tactical approach included forging alliances, utilizing superior artillery, and implementing disciplined military strategies. His forces faced challenges such as familiar terrain, local support for James II, and the complexities of executing a landing in hostile territory, but William managed to establish a foothold in Ireland, setting the stage for subsequent battles. The conflict culminated later with the famous Battle of the Boyne in July of the same year, which further determined the political landscape of Britain and Ireland.

Throughout this campaign, William of Orange was portrayed as a champion of Protestantism, while James II was increasingly seen as a figure of Catholic oppression. The dynamics established during this period would resonate through Irish and British history, influencing religious affiliations, governance, and nationalism in both regions for centuries to come. The Williamite policies would lead to the establishment of Protestant Ascendancy, altering the social and political fabric of Ireland in profound ways.