Flying with Benno Fiala Ritter von Fernbrugg as his observer, Heyrowsky shot down the Italian airship M4 in flames on 4 May 1916 with 53 incendiary bullets. Even as Heyrowsky was reopening his victory list, he was also volunteering to serve as an infantry officer in the ongoing Battle of Isonzo in his time off from flying. His leadership of his assigned company was responsible for its blocking an Italian offensive in the Sixth Battle of the Isonzo.