Scottish theologian and leader of the Reformation in Scotland, John Knox entered Catholic priesthood but became a Protestant under the influence of George Wishart, a Scottish Reformer. During the years of political and religious turmoil in Scotland, Knox was captured by French forces and held prisoner. From this experience, he emerged as the voice of the Scottish Reformation. After his release from prison, he worked with the Protestant regency ruling for Edward IV in England and helped shape The Book of Common Prayer. When the Catholic Mary Tudor came to the English throne, Knox left England and eventually moved to Geneva, where he met John Calvin. In Calvin's teachings, he found the ideals of the true Protestant church. He strove towards wiping out the vestiges of Catholicism in Scotland. To achieve this, he reasserted Calvin's conviction of the people's right to overthrow any ruler who curtailed their freedom of conscience. Back in Scotland, he led a group of Protestant nobles intent on overthrowing Catholic regent Mary Stuart. As the leader of the Reform movement and backed by the Scottish Parliament, he framed the Confession of Faith and summoned the first General Assembly of the Reformed Church. By the time of his death, Catholicism in Scotland had been vanquished.