Complex sentence: During World War II the Sound was known as "the Slot" by Allied combatants due to its geographical shape and the amount of warship traffic which traversed it; the Japanese naval efforts to resupply their garrison on Guadalcanal were referred to as the Tokyo Express.
Split into simpler sentences: During World War II the Sound was known as "the Slot" by Allied combatants due to its geographical shape and the amount of warship traffic that traversed it. The Japanese naval efforts to resupply their garrison on Guadalcanal were referred to as the Tokyo Express.