Henry III decided that Bedford Castle should be returned to its original owner, William de Beauchamp, and became increasingly frustrated with Falkes' refusal to do so; matters came to a head when Falkes' castellans imprisoned Henry of Braybrooke, a royal judge who was hearing law cases against Falkes. When Falkes refused to release the judge, Henry mobilised an army, supported by the Church in the form of Stephen Langton, the Archbishop of Canterbury, and advanced to Bedford. Falkes had left the castle, along with around eighty men, in charge of his brother, William de Breauté, who refused to surrender it to the king. Falkes was probably hoping that if the castle held on long enough, his efforts to convince Pope Honorius III to intervene against Henry would succeed. The Archbishop excommunicated William and the siege began.