 Under normal conditions, infantry could be expected to march in six hours, while it would take an artillery battery 10 hours to march .At the Battle of Antietam on 17 September 1862, the Federal Army of the Potomac employed 22 20-pounder Parrott rifles while the Confederate Army of Northern Virginia had none.The 5th New York Independent Light Artillery (Taft's) and 1st New York Light Artillery Battalion, Batteries A (Wever's), B (von Kleiser's), and C (Langner's) were all 4-gun 20-pounder Parrott batteries belonging to the V Corps.