Complex sentence: Their intention was to parachute into Crete but after arriving at the drop zone only Leigh Fermor was able to parachute successfully the others had to abandon the attempt due to bad weather and were returned to Egypt.
Split into simpler sentences: Their intention was to parachute into Crete but after arriving at the drop zone only Leigh Fermor was able to parachute successfully. The others had to abandon the attempt due to bad weather and were returned to Egypt.