Once formed, the regiment was attached to Major General John Adams Dix's division of the Army of the Potomac.

The regiment was originally commanded by Colonel James Wallace, a slaveowning lawyer and state legislator from Cambridge.

In the fall of 1861, Dix led an expeditionary force, including the 1st Maryland Eastern Shore, south to occupy the Virginia counties of Accomack and Northampton.

[2] The regiment arrived at the Battle of Gettysburg on the morning of July 3 and engaged the 1st Maryland Infantry, CSA[5] on Culp's Hill, suffering 5 dead, 16 wounded, and 2 missing, out of 583 total men.

[4] In December 1863, Colonel Wallace resigned his command over the issue of enlisting African-Americans in the army.