The 7th was assigned to the Army of the Potomac soon after it was formed and served in the 3rd Brigade, 2nd Division, 2nd Corps, for the duration of the war. Sister regiments in the 3rd Brigade included the 19th Massachusetts, 20th Massachusetts, 42nd New York, and 59th New York.
Infantryman William Rufus Shafter was wounded at the Battle of Fair Oaks; he later received the Medal of Honor for heroism during the battle.
The 7th was one of the first regiments to cross the Rappahannock River on Dec. 11th, 1862 while under fire from Confederate sharpshooters hidden in the buildings of Fredericksburg, the first opposed riverine assault in American military history.
In July 1862, Norman J. Hall, a Regular Army artilleryman assumed command of the regiment and led it until he was promoted to brigade command before the Battle of Gettysburg.
The regiment was mustered out on July 5, 1865.