This was all the more insisted upon, as that indefatigable demagogue, having, after his banishment, obtained the protection of certain counts of the Campagna, still continued to exercise from his place of refuge the most pernicious influence over the popular mind in Rome. Frederic readily undertook to do a service, which agreed as well with his personal feeling as with his policy. For Arnold of Brescia, on the election of the Duke of Swabia to the German throne, had written him a letter, inviting him to come and receive the imperial crown from the senate in contempt of the pope, but couched in such arrogant and fanatical terms, as highly to incense the king, who refused to listen to it; whereupon, Arnold aggravated his offence, by announcing that he would persuade the Romans to choose an emperor of their own, and throw up their allegiance to foreign ones. The plan which Frederic took to seize Arnold, was, first of all, to send a body of troops to waylay and capture one of the chiefs of the lawless counts of the Campagna, who had been mainly instrumental in liberating the arch-republican out of the hands of the papal officers, into which he had shortly fallen before at Oriculum; and then to threaten the speedy execution of the prisoner, unless Arnold were given up as a ransom. This plan succeeded. The other Campagnian counts, frightened at the resolute conduct of Frederic, and trembling at the consequences of his further anger, if the ransom demanded were not given, soon brought their client, whose revolutionary doctrines so much promoted those disorders by which they thrived, to the feet of the king, and received back their brother in exchange. Arnold was forthwith remanded in chains to Rome, there to await the arrival of Frederic, who intended to have the culprit tried before his own tribunal.