The 6th Regiment Massachusetts Volunteer Militia was a peacetime infantry regiment that was activated for federal service in the Union army for three separate terms during the American Civil War (1861-1865). The regiment gained notoriety as the first unit in the Union Army to suffer fatal casualties in action during the Civil War in the Baltimore Riot and the first militia unit to arrive in Washington D.C. in response to President Abraham Lincoln's initial call for 75,000 troops. Private Luther C. Ladd of the 6th Massachusetts is often referred to as the first Union soldier killed in action during the war.