In 1685 James II became King of England. James was a Catholic but the majority of the population in the country was Protestant. When James's wife gave birth to a son the English parliament feared that the next king would also be Catholic. Parliament invited James's daughter Mary, who was a Protestant, to take over the throne. Mary and her husband, William of Orange, landed in England in 1688 and prepared to overthrow James.

James looked to France and Ireland for support as he had little support in England . Louis XIV, the French king, was a great enemy of William's. The Irish army and the majority of the population were loyal to James. He decided to gather an army in Ireland and launch an invasion of England from there.