Complex sentence: As it stood, three air divisions were to defend German air space.The 3rd Fighter Division was the first line of defence, protecting Germany's air space at the French border stretching to Luxembourg and into western Belgium.
Split into simpler sentences: As it stood, three air divisions were to defend German air space. Jagddivision was the first line of defence, protecting Germany's air space at the French border stretching to Luxembourg and into western Belgium.