Complex sentence: Boelcke suffered a gun jam but Immelmann caught up with one of the raiders and shot down a B.E.2c, flown as a bomber, without an observer or Lewis gun, the pilot armed only with an automatic pistol.
Split into simpler sentences: Boelcke suffered a gun jam but Immelmann caught one of the raiders and shot it down. His victory was over a B.E.2c, flown as a bomber, without an observer or Lewis gun, the pilot armed only with an automatic pistol.