The trouble that the Jews were in under Caligula, prevented their thinking so much of persecuting the Christians; and thus the Church of Christ had a little rest, and went on increasing. But now that Herod Agrippa had become King of Judæa, it was different; for he, seeing the number of Christians increasing in a most extraordinary manner, was fearful that they might rebel, and refuse to obey him as their king: therefore we read, "Now about that time Herod the king stretched forth his hands to vex certain of the church. And he killed James the brother of John with the sword. And because he saw it pleased the Jews, he proceeded further to take Peter also." Herod was anxious to gain favour with his Jewish subjects; and there was no more certain way of doing so, than by persecuting the Christians. Having therefore killed one of the sons of Zebedee, he determined to take Peter, who was one of the chief amongst the Apostles. "Then were the days of unleavened bread"--that is, the Feast of the Passover was now drawing near; and the preparation for that Holy Sacrifice had already begun, by the putting away of leaven out of every Jewish house, according to the Law of Moses. "And when Herod had apprehended Peter, he put him in prison, and delivered him to four quaternions of soldiers to keep him; intending after Easter to bring him forth to the people," with the intention, no doubt, of slaying him, as he had already slain James. Four soldiers formed a quaternion; four quaternions therefore were sixteen men, who were especially appointed to guard Peter. "Peter therefore was kept in prison: but prayer was made without ceasing of the church unto God for him": and the prayers of the saints were more effectual than all the precautions taken by Herod. It was customary with the Romans to fasten a prisoner to his keeper by a light chain, which went round the wrist of each; thus rendering it impossible for the prisoner to move without the knowledge of his keeper. For greater security, Peter was thus bound to two of the soldiers.