Marshall S. Phillips of Auburn mustered in to Co. K of the 5th Maine Infantry on June 24, 1861. When his three-year enlistment ended, he was mustered out on July 27, 1864.
Phillips was a shoemaker before the war. He wrote to his wife, Diana Phillips, from Washington, D.C., the General Hospital in Philadelphia, and various camps in the South, concerning the health of his four children, money matters, and references to his participation in battles with the 5th Maine Infantry Regiment.
The regiment, one of the first Maine regiments to be mustered into service, was sometimes called the Forest City Regiment. It became part of the Sixth Corps of the Army of the Potomac and was involved in 22 battles.