A b s t r a c t: This article is an attempt to illustrate relations between the theory and practice of the military activity of Polish bishops under the rule of the Piast dynasty. The problem is discussed based on an analysis of the locally formulated ideal of episcopal power and the ideological and legal patterns reaching Poland that regulated the possibilities of using weapons by clergymen, and, in particular, defined the ways in which churchmen participated in wars and in declaring and conducting them. K e y w o r d s: bishops and war; warrior-bishop, ideals of episcopal power; canon law; clerical arms-bearing; episcopal warfare; Piast Poland.