The majority of this material was donated by Charles W. Brooks on May 21, 1913. The Philip M. Fowler diary was a gift from Clifton A. Sibley on April 6, 1981.

The 23rd Regiment Massachusetts Volunteer Infantry was organized at Camp Schouler in Lynnfield, Massachusetts in September 1861 and the first men were mustered in on September 28, 1861. Several of the ten companies that comprised the regiment were organized by men who had previously served in 90 days' of service. Company A from Salem was captained by Ethan A. P. Brewster. Company B from Marblehead was captained by Knott V. Martin. Company C from Gloucester was captained by Addison Center. Company F from Salem was commanded by Captain George M. Whipple. This company was also known as the Union Drill Club of Salem, which had organized as a social and then military organization earlier in 1861. The regiment left for Annapolis, Maryland in November 1861, intended as a part of the Burnside Expedition and by 1862 were stationed in Newbern, North Carolina.

This series is arranged into four subseries. Subseries A. General Regiment Records includes an order book, loose orders, and clothing receipts for the 23rd Regiment. Subseries B. Company A includes descriptive books and morning report books for Company A. Subseries C. Company B includes clothing accounts, morning report books and order books for Company B. Subseries D. Company C includes returns and invoices for clothing and equipment, along with bills paid, and correspondence for Company C. Subseries E. Company F includes enlistment records, receipts and invoices for Company F, along with scrapbooks and diaries created by William F. Chapple and Philip M. Fowler, members of Company F.