Complex sentence: On September 9, a large part of this unit was captured at Cumberland Gap by Union General Ambrose Burnside, which led to many of the captured men being sent to Louisville, Kentucky then later to Camp Douglas (Chicago).
Split into simpler sentences: On September 9, a large part of this unit was captured at Cumberland Gap by Union General Ambrose Burnside. Which led to many of the captured men being sent to Louisville, Kentucky then later to Camp Douglas (Chicago).