Complex sentence: The other two divisions available in reserve, the American 82nd and 101st Airborne, were already at Rheims in northern France, and the 6th Airborne rested and re-trained after their success in Normandy was sent from England by sea to Belgium to assist in the defence.
Split into simpler sentences: The other two divisions available in reserve, the American 82nd and 101st Airborne, were already at Rheims in northern France. A the same time the 6th Airborne rested and re-trained after their success in Normandy was sent from England by sea to Belgium to assist in the defence.