Sir Thomas More was an advisor to King Henry VIII. He disapproved of the king divorcing his first wife Catherine of Aragon in order to marry Anne Boleyn, without the approval of the Pope. Moore was a devout Catholic, and believed deeply in the supremacy of the Pope. In 1532, when he saw that King Henry was determined to marry Anne Boleyn and that divorce was in the air, he claimed ill health and retired, rather than stay in the king’s cabinet.
Things became worse when the king invited him to his marriage with Boleyn, and More declined to attend. He was summoned to the court to answer an obscure charge of accepting a bribe, which was later dropped. Henry then passed a law which declared him supreme ruler of the world, baring none, including the Pope. All citizens were to take an oath recognizing this, but More refused.
Henry VIII threw him into the Tower of London, where for a whole year, he was locked up. His wife and children visited him and begged him to take the oath, but More refused on principle. He was tried for treason, found guilty, and beheaded.