On 1 July 1690 (Old Style), King William III clashed with his father-in-law, King James II, on the River Boyne at Oldbridge, County Meath. Both kings commanded their armies in person.

There were 36,000 men on the Williamite side and 25,000 on the Jacobite side. It was the largest number of troops ever deployed on an Irish battlefield.

At stake were the British throne, French dominance in Europe and religious power in Ireland. William was victorious – and the continent was changed forever.