1st Maryland, PHB

The First Regiment, Potomac Home Brigade, was a militia unit recruited in western Maryland and from Unionists in neighboring Loudoun County, Virginia. In the spring of 1862 the Regiment was with General Banks' Division in the Shenandoah Valley and then guarded the Baltimore and Ohio Railroad in Maryland and Virginia. In May 1862, they were assigned to Harpers Ferry. On the 27th they skirmished with Confederates at Loudoun Heights, Va. Detachments continued on duty along the B&O RR.

In August, the regiment was part of the Federal force watching the Potomac between Sandy Hook and the mouth of the Monocacy. They were ordered into the garrison at Harpers Ferry on 5 September after the first of the Confederate units crossed the Potomac, beginning the Maryland Campaign.

They were captured with the rest of the garrison on 15 September and paroled on the 16th to Annapolis, Maryland.

They were exchanged and served in Southern Maryland until the Gettysburg Campaign, where they were in action with the XIIth Army Corps. They took heavy losses in action on the Federal right on the 3rd day there, across the line from the 1st Maryland Infantry (Confederate) .

They returned to duty along the B&O until Early's raid of July 1864, when they saw action at the battle of Monocacy on 9 July.

The regiment's terms of service expired and most men were mustered out by December, 1864. Additional recruiting brought the core of veterans and newer recruits up to a full regiment, becoming the 13th Maryland in April 1865.

Basic unit data above from Wilmer.1