The campaign was unfortunate from the beginning. Nevertheless, but one of the associated knights saw that the moment was inopportune. The rest were confident of success, and a pretext was speedily found in the fact that Sickingen's feudal superior, the Archbishop of Trier (Treves), had refused to compel two councillors of that city to repay him 5000 Rhenish guilders (_gulden_) which he had paid as ransom for them to a certain knight, Gerhard Börner, who had taken them prisoners. This was a sufficient _casus belli_ for those times; and Sickingen thereupon issued a manifesto in which he declared himself the champion of the gospel, and announced his intention to free the subjects of the archbishop from the temporal yoke of their tyrant, who had acted against God and the imperial majesty, and from the spiritual yoke of godless priests, and to place them in possession of that liberty which the gospel (_i.e._, the new gospel of Luther) alone could afford. It should be premised that on the 13th of August, previous to this declaration of war, a "Brotherly Convention" had been signed by a number of the knights, by which Sickingen was appointed their captain, and they bound themselves to submit to no jurisdiction save their own, and pledged themselves to mutual aid in war in case of hostilities against any one of their number. Through this "Treaty of Landau," Sickingen had it in his power to assemble a considerable force at a moment's notice. Consequently, a few days after the issue of the above manifesto, on the 27th August, 1522, Sickingen was able to start from the Castle of Ebernburg with an army of 5000 foot and 1500 knights, besides artillery, in the full confidence that he was about to destroy the position of the Palatine prince-prelate and raise himself without delay to the chief power on the Rhine. The grand chamberlain of the celebrated patron of letters and Humanism, Albrecht, Archbishop of Mainz, Frowers von Hutten, was in the conspiracy; and it is almost certain that Albrecht himself was secretly in accord with Sickingen's plan for the destruction of his electoral neighbour. This is shown by the fact that when the Archbishop of Trier appealed to him, as his colleague, for assistance, Albrecht made a number of excuses which enabled him to delay the sending of reinforcements until they were too late to be of any use, whilst at the same time numbers of his retainers and subjects served under Sickingen's banner.