Complex sentence: Galland himself flew on unauthorised interception flights to experience the combat pressures of the pilots, and witnessed USAAF bombers being escorted by large numbers of North American P-51 Mustangs.
Split into simpler sentences: Galland himself flew on unauthorised interception flights to experience the combat pressures of the pilots. Galland witnessed USAAF bombers being escorted by large numbers of North American P-51 Mustangs.