Together, Hutten and Sickingen formulated a series of suggested reforms calling for the abolition of all independent principalities, for the unification of all German-speaking lands under one national government, the secularization of all church principalities and estates, and establishment of a "noblemen's democracy headed by a monarch." Hutten and Sickingen hoped that this program would be sufficient to encourage the peasantry to enthusiastically join the knights in bringing about reform. Under Hutten's influence, Sickingen's castle of Ebernburg became a centre of Renaissance humanist and later Lutheran thinking, with many pamphlets emanating from the castle. Sickingen helped Johann Reuchlin escape from the Dominicans of Cologne, and sheltered other reformers such as Martin Bucer and Johannes Oecolampadius. He even offered shelter to Martin Luther after the Diet of Worms, but Luther chose to stay with Frederick of Saxony instead. Revolt Siege of Trier In 1522, while the Emperor was in Spain, Sickingen convened a "Brotherly Convention of Knights." The Convention elected him as their leader, and resolved to take by force that which the knights had been unable to obtain through their poor representation in the Reichstag. The target chosen by the knights to start their revolt was Richard von Greiffenklau zu Vollrads, Archbishop of Trier, a staunch opponent of Luther and his supporters. The excuse used for the attack was an unpaid ransom by two city councillors to another knight who had captured them some years ago. Sickingen’s declaration of war was full of religious rhetoric designed to encourage the people of the city to surrender and overthrow their archbishop, and so save the knights the trouble of a siege. Sickingen assembled an army partly on his own and partly with the help of neighboring knights. Sickingen had his soldiers fly the Imperial flag, and he claimed he was acting on behalf of the Emperor. However, the Imperial Diet in Nuremberg which was acting as regent during the absence of Charles V, did not agree, and ordered him to stop his campaign under threat of an imperial ban. The campaign was launched in the autumn, which indicates that Sickingen did not intend to press on further that year. Sickingen ignored the Diet, however, and pressed on to Trier. Unfortunately for him, the people of the city did not revolt against Richard, and Richard proved to be an able soldier. In addition, the Count palatine and the Landgrave of Hesse came to