The 31st Maine Regiment was mustered in for three years' service on April 17, 1864 and were mustered out on August 20, 1865. Of the 1595 men enrolled in the regiment, 183 were killed or died of wounds, 491 were wounded, 176 died of disease, and 34 were in Confederate prisons.

They served in the following engagements:

• Wilderness, VA - May 5-7, 1864
• Spotsylvania, VA - May 7-20, 1864
• North Anna, VA - May 23-27, 1864
• Totopotomy, VA - May 26-30, 1864
• Bethesda Church, VA - May 30-June 1, 1864
• Cold Harbor, VA - May 31-June 12, 1864
• Petersburgh, VA - June 1864-March 1865
• Battle of the Crater, VA - July 30, 1864
• Weldon Railroad, VA - August 18-21, 1864
• Poplar Spring Church, VA - September 30-October 2, 1864
• Hatchers Run, VA - December 8 - 9, 1864