The 104th Infantry Regiment traces its history to 14 November 1639, when it was first mustered as the Springfield Train Band in Springfield, Massachusetts. In 1662 the unit was formed into the Hampshire Regiment of the Massachusetts Militia. It later served in the Continental Army during the American Revolution, with Union forces in the American Civil War, and as a federalized Massachusetts National Guard regiment with the U.S. Army during Spanish–American War, Mexican Border Campaign, World War I and World War II. The last active element of the regiment, the 1st Battalion, was deactivated in 2005 and the soldiers and lineage transferred to the 1st Battalion, 181st Infantry Regiment.