James, Duke of York was the title held by King James II before he became the king of England. James Stuart was titled as the Duke of York in 1644, and eventually ascended the throne in 1685, following the death of his brother, King Charles II. Full of controversy, James' rule of England was short lived however, only lasting until 1688.
King James II's reign was troubled by the political and religious turmoil of the the time, as the Parliament and the people strove to keep the Protestant way of life alive in England. Though James never tried to press his own Catholicism on the country, when he married his second wife (a Catholic princess), Parliament worried that conversion was imminent. Rebelling, the nobles of England called for James' own son-in-law, William of Orange, to invade and remove James from the throne. James' daughter, Mary II, and William took over the throne when James fled, abdicating the throne.