 Of the 1,100 who initially belonged to the unit, only 125 returned at the end of their three years of service.Of these losses, roughly 300 were killed in action or died from wounds received in action, approximately 500 were discharged due to wounds or disease, and approximately 175 were lost or discharged due to capture, resignation, or desertion.Henry Wilson, a Senator from Massachusetts and chairman of the Senate's Committee on Military Affairs, witnessed the First Battle of Bull Run on July 21, 1861.