During September 1939, Slovakia participated in the German Invasion of Poland; the nation held the aim of regaining territories which had been previously lost to Poland at Munich. A pair of squadrons of B-534s were assigned to support the invasion. In the theatre, these were typically used to escort "Luftwaffe" aircraft, such as the Junkers Ju 87 dive-bomber, on eight missions, during which a pair of B-534s were lost while the downing of a single Polish RWD-8 liaison aircraft was claimed.