Complex sentence: If so, the guns would have a range of about and could threaten Sword Beach, to the west of Ouistreham, where the 3rd British Infantry Division were due to land later that day.
Split into simpler sentences: If so, the guns would have a range of about. At this distance, they could threaten the 3rd British Infantry Division's landing area, codenamed Sword, to the west of Ouistreham, where were due to land later that day.