Complex sentence: On 3 June, the French units were warned an hour before the German bombers took off, but owing to equally poor staff work, few French Squadrons heard the scramble signal when it was radioed from the Eiffel Tower and some were caught on the ground.
Split into simpler sentences: On 3 June, the French units were warned an hour before the German bombers took off. But owing to equally poor staff work, few French Squadrons heard the scramble signal when it was radioed from the Eiffel Tower and some were caught on the ground.