The 2nd United States Sharpshooters, Company D (Maine) organized November 2, 1861 and defended Washington, D.C., until April 1862. From 1861 to January 1863 they were members of the "First Iron Brigade" also known as the "Iron Brigade of the East". The regiment was broken up on February 20, 1865, and Company "D" transferred to the 17th Maine Volunteer Infantry Regiment. The regiment suffered loss of 8 officers and 117 enlisted men who were killed in action or mortally wounded and 2 officers and 123 enlisted men who died of disease, for a total of 250 fatalities.

The company served in the following engagements:

• Falmouth, VA
• Rappahannock Station, VA
• Groveton, VA
• 2nd Manassas (Bull Run), VA - August 29-30, 1862
• South Mountain, MD
• Antietam, MD - Sept. 17, 1862
• Fredericksburg, VA - Dec. 13, 1862
• Chancellorsville, VA - May 1-4, 1863
• Gettysburg, PA - July 1-3, 1863
• Wapping Heights, VA - July 21-23, 1863
• Auburn, VA
• Kelly's Ford, VA - Nov. 7, 1863
• Locust Grove, VA
• Mine Run, VA
• Wilderness, VA
• Spottsylvania, VA
• Po River, VA
• Fredericksburg Pike, VA
• North Anna, VA
• Totopotomy, VA
• Cold Harbor, VA
• Weldon Railroad, VA
• Petersburg, VA
• Strawberry Plains, VA
• Deep Bottom, VA
• Jerusalem Plank Road, VA
• Peebles Farm, VA
• Poplar Spring Church, VA
• Hatchers Run, VA
• Boydton Road, VA