Complex sentence: Co-operation with ground units was vital during sorties around this time and during one mission Flight Lieutenant McFall, carrying out a Lysander reconnaissance, located the enemy unit and then landed beside Allied gun batteries in order to direct the fire.
Split into simpler sentences: Co-operation with ground units was vital during sorties around this time. During one mission, Flight Lieutenant McFall, carrying out a Lysander reconnaissance, located the enemy unit and then landed beside Allied gun batteries in order to direct the fire.