Why was Saint Thomas More a martyr?

Saint Thomas More (1478 - 1535), husband and father and a Catholic, was Chancellor of England. When King Henry VIII declared himself to be Head of the Church in England, Thomas More and many other English subjects hoped that a way could be found whereby they could continue to be the loyal subjects of the King as Head of State, while remaining loyal Catholics, looking to the Pope as Head of the Church. It soon became clear, however, that those holding political and church offices would be forced to renounce any allegiance to the Pope, or die. Thomas More resigned the Chancellorship and retired to his home, citing ill health, but his absence from Court was noted and resented. Charges of treason against the king were brought against him; he was found guilty and executed by beheading. His last Words on the scaffold were, "I die the king's good servant, but God's first."