Complex sentence: Built prior to World War II as a civil airport, Vernouillet Airport was seized by the Germans in June 1940 during the Battle of France, and was used as a major Luftwaffe military airfield during the occupation.
Split into simpler sentences: Built prior to World War II as a civil airport, Vernouillet Airport was seized by the Germans in June 1940 during the Battle of France. They used it as a major Luftwaffe military airfield during the occupation.