The stubborn opposition of the Polish hierarchy to share in the burden of defense in this mild form caused the Polish nobility to stiffen its demands. Since the Polish bishops so strenuously objected to the participation of the mayors of ecclesiastical villages in the pospolite ruszenie, the szlachta came forward at the Diet of Thorn in 1520 with the demand that the clergy as a class be put on the same level as the secular nobility in regard to military service.[419] All the clergy in possession of landed estates were to participate in the pospolite ruszenie along with the szlachta. This demand was renewed and firmly insisted upon at a local diet of the nobility of Great Poland at Kolo in 1533, at the General Diet of 1535,[420] and even as late as 1562 at the Diet of Piotrków.[421] This summary demand on the part of the Polish nobility that the clergy as a landowning class share equally with the szlachta the burden of defense startled the clergy, and finally induced them to present their documentary privileges, on which they based their claim of exemption from the burden of defense at the subsequent Diet of Piotrków, which met in the fall of 1563. On examination these documents were found to be anything but explicit and clear; yet the nobility had relented by this time, and ceased pressing this particular demand any further.[422] Owing to this stubborn opposition on the part of the clergy to their personal participation in military service and to that of the bailiffs of ecclesiastical villages as well, the Polish nobility turned its attack now directly upon the landed property and the incomes of the clergy. In 1534 and in 1535 it vehemently protested against the purchases of village bailiwicks by the clergy. In 1536-1537, at the Diet of Piotrków, it went still further, and urgently demanded the secularization of all ecclesiastical property. As a result of this determined stand, a plan was actually agreed upon between the Chamber of Deputies and the secular members of the Senate for partial secularization of church lands. According to this plan all ecclesiastical lands acquired by the clergy whether by gift or by purchase since Louis the Great, 1370-1382, were to be sold to the nobility.[423] The demand for the secularization of ecclesiastical estates was first made in the first half of the fifteenth century, then in 1524, with increasing vigor and insistence at the Diet of Piotrków in 1536-1537, and again in 1576.[424] How determined the Polish nobility was to get hold of the property of the clergy may be seen from the fact that in 1539, when the old king, Sigismund I, was critically ill, a conspiracy was actually formed, the purpose of which was not to recognize Sigismund Augustus in the event of his father’s death until he agreed to and sanctioned the confiscation of one-third of the church lands for purposes of national defense.[425] The leaders in this conspiracy, as well as in the rebellion of 1537, were Martin and Peter