23mm, Massachusetts Volunteer Militia 3pc Staff Coat Button with a "Treble Gilt" backmark. The shank is missing, but the rest of the button is in good shape (and would brighten up more with gentle cleaning).

During the Civil War, Massachusetts Volunteer Militia units, like the 6th and 4th regiments, played a crucial role in the Union effort, participating in key battles and deployments, including the Baltimore Riot and the Siege of Port Hudson.