The head of the Kildare FitzGeralds held the position of lord deputy until 1534. The problem was that the House of Kildare had become unreliable for the English monarch, scheming with Yorkist pretenders to the English throne, signing private treaties with foreign powers, and finally rebelling after the head of its hereditary rivals, the Butlers of Ormonde, was awarded the position of lord deputy. The Reformation also led to growing tension between England and Ireland as Protestantism gained sway within England. Thomas, Earl of Kildare, a fervent Catholic, offered control of Ireland to both the Pope and Emperor Charles V of the Holy Roman Empire. Henry put down the rebellion by executing the leader ("Silken Thomas" FitzGerald), along with several of his uncles, and imprisoned Gearóid Óg, the head of the family. But now the king had to find a replacement for the FitzGeralds to keep Ireland quiet. What was needed was a cost-effective new policy that protected the Pale and guaranteed the safety of England's vulnerable west flank from foreign invasion.