The mental attitude of the knighthood in the face of this progressing change in their position was naturally an ambiguous one, composed partly of a desire to hark back to the haughty independence of feudalism, and partly of sympathy with the growing discontent among other classes and with the new spirit generally. In order that the knights might succeed in recovering their old or even in maintaining their actual position against the higher nobility, the princes, backed as these now largely were by the imperial power, the co-operation of the cities was absolutely essential to them, but the obstacles in the way of such a co-operation proved insurmountable. The towns hated the knights for their lawless practices, which rendered trade unsafe and not infrequently cost the lives of the citizens. The knights for the most part, with true feudal hauteur, scorned and despised the artisans and traders who had no territorial family name and were unexercised in the higher chivalric arts. The grievances of the two parties were, moreover, not identical, although they had their origin in the same causes. The cities were in the main solely concerned to maintain their old independent position, and especially to curb the growing disposition at this time of the other estates to use them as milch cows from which to draw the taxation necessary to the maintenance of the Empire. For example, at the Reichstag opened at Nürnberg on the 17th November, 1522—to discuss the questions of the establishment of perpetual peace within the Empire, of organising an energetic resistance to the inroads of the Turks, and of placing on a firm foundation the Imperial Privy Council (Kammergericht) and the Supreme Council (Reichsregiment)—at which were represented twenty-six imperial towns, thirty-eight high prelates, eighteen princes, and twenty-nine counts and barons—the representatives of the cities complained grievously that their attendance was reduced to a farce, since they were always out-voted, and hence obliged to accept the decisions of the other estates. They stated that their position was no longer bearable, and for the first time drew up an Act of Protest, which further complained of the delay in the decisions of the imperial courts; of their sufferings from the right of private war which was still allowed to subsist in defiance of the constitution; of the increase of customs-stations on the part of the princes and prince-prelates; and, finally, of the debasement of the coinage due to the unscrupulous practices of these notables and of the Jews. The only sympathy the other estates vouchsafed to the plaints of the cities was with regard to the right of private war, which the higher nobles were also anxious to suppress amongst the lower, though without prejudice of course to their own privileges in this line. All the other articles of the Act of Protest were coolly waived aside. From all this it will be seen that not much co-operation was to be expected between such heterogeneous bodies as the knighthood and the free towns, in spite of their common interest in checking the threateningly advancing power of the princes and the central imperial authority, which was for the most part manned and manipulated by the princes.
Amid the decaying knighthood there was, as we have already intimated, one figure which stood out head and shoulders above every other noble of the time, whether prince or knight; and that was Franz von Sickingen. He has been termed, not without truth, "the last flower of German chivalry," since in him the old knightly qualities flashed up in conjunction with the old knightly power and splendour with a brightness hardly known even in the palmiest days of mediæval life. It was, however, the last flicker of the light of German chivalry. With the death of Sickingen and the collapse of his revolt the knighthood of Central Europe ceased any longer to play an independent part in history.
Sickingen, although technically only one of the lower nobility, was deemed about the time of Luther's appearance to hold the immediate destinies of the Empire in his hand. Wealthy, inspiring confidence and enthusiasm as a leader, possessed of more than one powerful and strategically-situated stronghold, he held court at his favourite residence, the Castle of the Landstuhl, in the Rhenish Palatinate, in a style which many a prince of the Empire might have envied. As honoured guests were to be found attending on him, humanists, poets, minstrels, partisans of the new theology, astrologers, alchemists, and men of letters generally; in short, the whole intelligence and culture of the period. Foremost among these, and chief confidant of Sickingen, was the knight, courtier, poet, essayist and pamphleteer, Ulrich von Hutten, whose pen was ever ready to champion with unstinted enthusiasm the cause of the progressive ideas of his age. He first took up the cudgels against the obscurantists on behalf of Humanism as represented by Erasmus and Reuchlin, the latter of whom he bravely defended in his dispute with the Inquisition and the monks of Cologne, and in his contributions to the Epistolæ Obscurorum Virorum we see the youthful ardour of the Renaissance in full blast in its onslaught on the forces of mediæval obstruction. Unlike most of those with whom he was first associated, Hutten passed from being the upholder of the New Learning to the rôle of champion of the Reformation; and it was largely through his influence that Sickingen took up the cause of Luther and his movement.
Sickingen had been induced by Charles V. to assist him in an abortive attempt to invade France in 1521, from which campaign he had returned without much benefit either material or moral, save that Charles was left heavily in his debt. The accumulated hatred of generations for the priesthood had made Sickingen a willing instrument in the hands of the reforming party and believing that Charles now lay to some extent in his power, he considered the moment opportune for putting his long-cherished scheme into operation for reforming the constitution of the Empire. This reformation consisted, as was to be expected, in placing his own order on a firm footing, and of effectually curbing the power of the other estates, especially that of the prelates. Sickingen wished to make the Emperor and the lower nobility the decisive factors in his new scheme of things political. The Emperor, it so happened, was for the moment away in Spain, and Sickingen's colleagues of the knightly order were becoming clamorous at the unworthy position into which they found themselves rapidly being driven. The feudal exactions of their princely lieges had reached a point which passed all endurance, and since they were practically powerless in the Reichstags no outlet was left for their discontent save by open revolt. Impelled not less by his own inclinations than by the pressure of his companions, foremost among whom was Hutten, Sickingen decided at once to open the campaign.
Hutten, it would appear, attempted to enter into negotiations for the co-operation of the towns and of the peasants. So far as can be seen, Strassburg and one or two other imperial cities returned favourable answers; but the precise measure of Hutten's success cannot be ascertained, owing to the fact that all the documents relating to the matter perished in the destruction of Sickingen's Castle of Ebernburg. It is certain, however, that operations were begun before any definite assurances of help had been obtained, although had the first attempts had any appearance of success there is little doubt that such help would have been forthcoming.
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.
By an effective piece of audacity, that of sporting the imperial flag and the Burgundian cross, Franz spread abroad the idea that he was acting on behalf of the Emperor, then absent in Spain; and this largely contributed to the result that his army speedily rose to 5000 knights and 10,000 footmen. The Imperial Diet at Nürnberg now intervened, and ordered Sickingen to cease the operations he had already begun, threatening him with the ban of the Empire and a fine of 2000 marks if he did not obey. To this summons Franz sent a characteristically impudent reply,[21] and light-heartedly continued the campaign, regardless of the warning which an astrologer had given him some time previously, that the year 1522 or 1523 would probably be fatal to him. It is evident that this campaign, begun so late in the year, was regarded by Sickingen and the other leaders as merely a preliminary canter to a larger and more widespread movement the following spring, since on this occasion the Swabian and Franconian knighthood do not appear to have been even invited to take part in it.