Why did Henry the VIII appoint a new archbishop of Canterbury?

When William Warham, the Archbishop of Canterybury, died, Henry saw an opportunity to put someone in the Archbishopric that would be amenable to annulling his marriage to Catherine. He used his power as King to have Thomas Cranmer, the Archdeacon of Taunton, appointed to the position. Cranmer received the sanction of Pope Clement VII and then proceeded to lead Henry's reformation and split from the Holy Roman Church creating the Church of England. Henry got his divine annulment as well as excommunication for himself and Cranmer. Cranmer was put to death by burning for the crime of heresy in 1556, nine years after Henry's death.