It suffered the highest casualty count of any brigade in the history of the United States Army, with some 1,172 killed in action.
It was composed of the 2nd, 3rd, 4th, 5th and 6th Vermont regiments, which had been individually mustered into service between June and September, for a time, it also included the 26th New Jersey Infantry.
The Vermonters participated in VI Corps' capture of Marye's Heights in the Second Battle of Fredericksburg and then were prominent in the fighting at Salem Church.
They were held in reserve during the Battle of Gettysburg, holding a flank guard position behind Big Round Top, losing only one man wounded.
That same month, the Army of the Potomac, under the overall supervision of Lt. Gen. Ulysses S. Grant, began its spring offensive (the Overland Campaign) towards Richmond.
Hill's Confederate corps had been brought up and was attacking the weak Union center along the Orange Plank Road.
Maj. Gen. George W. Getty's brigades were ordered by Maj. Gen. Winfield S. Hancock, who was still bringing up most of his corps, to hold the road and counterattack.
Early in the battle, elements of the Vermont brigade, defending barricades forward of the rest of the Union Army, were ordered to retreat and spike their supporting artillery field pieces before the Confederates overran them.
Foster's brigade held the center of the division's line until the entire formation retreated in good order.
Returning to Petersburg, where it was engaged until the end of the war, the First Vermont Brigade led the attack on the earthworks defending the city, successfully breaking through the Confederate lines on the morning of April 2, 1865.