Complex sentence: During the Second World War, the reduced staff slept in the crypt to shelter from air-raids, and a German pilot was held there for a single night after parachuting onto the estate from his stricken plane.
Split into simpler sentences: During the Second World War, the reduced staff slept in the crypt to shelter from air-raids. A German pilot was held prisoner there for one night after parachuting onto the estate from his stricken plane.