 Complete the following phrase:  The 56th Regiment Massachusetts Volunteer Infantry was a regiment of infantry that served in the Union Army during the American Civil War. It was one of the four Veteran Regiments raised in the winter of 186364. Recruits of these regiments were required to have served at least nine months in a prior unit. The regiment was attached to the IX Corps of the Army of the Potomac and took part in Lieutet General Ulysses S. Grants Overland Campaign in the spring of 1864. They were in extremely heavy combat during the campaign, suffering great casualties during engagements which included the Battle of the Wilderness, Spotsylvania Courthouse, and the Battle of the Crater. They were involved in several assaults during the Siege of Petersburg in 1864 and participated in the spring 1865 battles which finally drove General Robert E. Lees Confederate Army from their entrenchments in Petersburg, leading to the end of the war at 