The 12th Regiment Massachusetts Volunteer Infantry was an infantry regiment in the Union army during the American Civil War. It was formed on June 14, 1861, in Boston, Massachusetts. Its original commander was Colonel Fletcher Webster, son of the famed U.S. Senator from Massachusetts, Daniel Webster. The unit was known as the Webster Regiment after its first colonel.

Fort Warren is a historic fort on the 28-acre (110,000 m2) Georges Island at the entrance to Boston Harbor. The fort is named for Revolutionary War hero Dr. Joseph Warren, who sent Paul Revere on his famous ride, and was later killed at the Battle of Bunker Hill. The name was transferred in 1833 from the first Fort Warren – built in 1808 – which was renamed Fort Winthrop.