3rd Regiment Massachusetts Volunteer Heavy Artillery

The 3rd Regiment of Massachusetts Volunteer Heavy Artillery was a unit that served in the Union Army during the American Civil War. It was organized from already mustered unattached companies of heavy artillery raised for the defenses of the Massachusetts coast.

History
Beginning in January 1863, and continuing until early 1864, twelve companies of heavy artillery were raised in Massachusetts and mustered into service to garrison the military forts along the coast of the state. The units were designated "unattached" as they did not belong to a particular regiment.

In the spring of 1864, the 3rd Unattached Company, along with the 6th through 12th, were ordered to Washington, DC, where they were to garrison the forts protecting the capital. Massachusetts' Governor Andrew called for the companies to be given regimental status, and when it was granted, several other companies since raised were sent to Washington to complete its complement, and was officially made a regiment in the fall of 1864. Except for Company I, the regiment continued with its duty of manning forts in the vicinity of the capital. A portion of the regiment was mustered out on 17 June 1865, while the remaining companies served until 18 September.

Company I

The 13th Unattached Company, which later became Company I, had been recruited in Springfield, MA and was largely composed of mechanics who were employed at the city's National Armory. Because of their engineering skills, they were detached from the regiment and attached to the Army of the James, and were engaged in building bridges and roads. During the Siege of Petersburg, they were in charge of holding the pontoon bridge placed across the James River. They were the last men of the regiment to be mustered out, doing so on 26 September 1865.

The Unattached Companies
The other unattached heavy artillery companies raised in Massachusetts, the 1st, 2nd, 4th and 5th, had become the 1st Battalion Massachusetts Volunteer Heavy Artillery in 1863.

Complement
The regiment consisted of 94 officers and 1803 enlisted men.

Losses
Two officers and 39 enlisted men died from disease or accident. None were killed in action.