According to a statute of Casimir the Great of the year 1347 the mayors of ecclesiastical villages as well as the mayors of secular villages were required to participate in military expeditions.[413] This obligation was reaffirmed by the Constitution of 1538,[414] and again in 1550.[415] But, as we have already noted, the clergy succeeded in evading these statutory provisions not only throughout the fifteenth, but also in the sixteenth century. It is not strange, therefore, to find that as the burden of defense was increasing in weight the Polish nobility repeatedly demanded that the mayors of ecclesiastical villages take part in the country’s defense in compliance with the law. The first demand of this nature in the sixteenth century was made as early as 1510; then we find it repeated at the Diet of 1536-1537; and again in 1563. In 1510 the king referred the question at issue to the provincial synod for review, and the synod was to report on it at a subsequent general diet.[416] But the matter was evidently laid aside and remained so as long as it was possible to keep it from coming to the front again; for when it was brought up at the Diet of 1536-1537, it was again treated in a similar manner. The bishops agreed to comply with the law, provided it was proved to them that the mayors of their villages were subject to military service. Their special privileges, which they claimed to possess, were to be examined at the following synod, and then the matter was to be reported on at the general diet.[417] Presumably the matter stopped there as before; for at the Diet of 1558-1559 the Chamber of Deputies raised the old question again, and demanded of the bishops the presentation of their special privileges exempting the mayors of ecclesiastical villages from military service. But even then the clergy did not produce this documentary evidence until at the Diet of 1563; and when actually produced, it was found wanting, owing to its indefiniteness.[418]