Complex sentence: The Glider Pilot Regiment was a specialist British unit of the Second World War which was responsible for crewing the British Army's cargo gliders and saw action in the European Theatre in support of Allied airborne operations.
Split into simpler sentences: The Glider Pilot Regiment was a specialist British unit of the Second World War. The Regiment was responsible for crewing the British Army's cargo gliders and saw action in the European Theatre in support of Allied airborne operations.