Complex sentence: When the Germans switched to night attacks, the Camel proved capable of being flown at night, and the home defence aircraft were modified with navigation lights to serve as night fighters.
Split into simpler sentences: When the Germans switched to performing their attacks during nighttime, the Camel proved capable of being flown at night as well. Accordingly, those aircraft assigned to home defence squadrons were quickly modified with navigation lights in order that they could serve as night fighters.