During the American Civil War the men of Brockport formed all of Company A (100 men) of the 140th New York Volunteer Infantry Regiment formed in September 1862 at Rochester, New York. Brockport's total population was little more than 2100 people at the time. Additional volunteers from Brockport helped form Company H of the 140th New York Volunteer Infantry Regiment. Company A's heroics helped secure the flank of the 5th Maine and stabilized a bad situation on Little Round Top at the Battle of Gettysburg. The 140th New York regiment also saw battle at the Battle of the Wilderness, the Battle of Spotsylvania Court House, and the Appomatox Courthouse Campaign. The 140th New York Volunteer Infantry Regiment was mustered out on June 3, 1865, near Alexandria, Virginia.