Why was Sir Thomas More imprisoned?

Thomas More fought any form of heresy, especially the incursion of Protestantism into England. He opposed King Henry VIII on the matter of royal divorce, and refused to swear the Oath of Supremacy which declared the king the head of the Church in England. Resigned the Chancellorship, and was imprisoned in the Tower of London where he was martyred for his refusal to bend his religious beliefs to the king's political needs.