IN THE FIFTEENTH-CENTURY Catalogue of the Bishops of Płock (Vitae Episcoporum Plocensium), which was originally written by the most eminent historiographer of the Polish Middle Ages, Jan Długosz (1415–1480), some information concerning military activity of the Mazovian bishops was included. Two pieces of information (related to bishops Simon and Alexander of Malonne) were based on the well-known twelfth-century chronicles of Gallus Anonymus and Master Vincentius of Kraków. The original accounts of these authors have already been the subject of an in-depth analysis by historians. The origins of two other accounts, however, are unknown. Although one of them, concerning Bishop Gunter, was noticed by scholars and even considered credible, the information contained therein was not analyzed in detail in the context of the Polish episcopate and warfare, as well as legal and social norms connected with it. The latter information, however, describing the activity of Bishop Gedko, did not attract any interest of scholars at all. It should be noted that Polish medieval historiography is not abundant in terms of the topics covered in this chapter, which is why every account, even not a very extensive one, is important for this research.

The Vitae Episcoporum Plocensium, completed by Jan Długosz at the end of 1477, only survives through the author's authentic preface from January 1, 1478. All that otherwise remains is a shortened text written at the beginning of the seventeenth century. The author of the edited version was doctor Laurentius of Wszerecz (1538–1614), a Płock penitentiary, who also wrote down the successive lives of the Płock bishops until 1608.

Długosz collected slightly random information about the bishops of Płock during the first and second editions of his most important work, Annales seu cronicae incliti regni Poloniae, which was being written from 1455 until his death in 1480. Only at the end of his life, however, did he carry out a specific query concerning the prelates of Mazovia, since he was planning to write the Catalogue. The result of his work was, at least partially, subsequently included into the Annales. Yet, it can be assumed that he may not have had enough time to use all the information due to his relatively imminent death.