In the second half of the fifteenth century there was a dynamic development in firearms. Improvements were made both to the artillery and firearms, as well as to the technique of using this type of weapon. In Central Europe, the war between the Kingdom of Poland and the Confederation of Prussian states with the Teutonic Order, known as the Thirteen Years War, served as a training ground for the development of firearms. The use of firearms and artillery in this conflict, during both field battles and, above all, during the numerous sieges of cities and castles, draws closer attention to the influence that these struggles have had on the defensive architecture of the Kingdom of Poland. This article analyses the defences of the headquarters of the most important Polish military commanders (such as Piotr Szamotulski, Piotr Dunin, Paweł Jasieński), created during the war and immediately after the war. The study demonstrated that the experiences of the Thirteen Years War were not fully exploited by its most important combatants on the Polish side. The majority of Polish noblemen (who were jointly commanders of mercenaries, state armies or mass levées) in the formulation or reconstruction of their headquarters emphasised prestige, so these often appear archaic from the military point of view, but with a representative form – the residential tower. Perhaps the reasons were economic considerations, or the belief that large military forces with strong artillery made small concentrations of resistance futile, so it was not worth investing in their excessive fortification. Only in the architecture of Peter Dunin’s castle in Ujazd are there visible attempts at the modernization of its defences, however, alongside the simultaneous development of the residential and representative zone.