Complex sentence: He served for 2 years in the NATO headquarters at Fontainebleau, and left the RAF in 1965.six years' service were spent at Nato headquarters at Fontainebleau.
Split into simpler sentences: He served for 2 years in the NATO headquarters at Fontainebleau, and left the RAF in 1965. Six years' service were spent at Nato headquarters at Fontainebleau.