The title was first granted to King Henry VIII after he passed the Act of Supremacy , which required all officials in the Church of England to state an oath of allegiance to him . By 1536 Henry VIII had broken with Rome , seized the church 's assets in England and declared the Church of England as the established church with himself as its head . The Act of Supremacy 1534 confirmed the King 's status as having supremacy over the church and required the nobility to swear an oath recognizing Henry 's supremacy .