 Moved back to Fortress Monroe in early June, they were then ordered to Newport News, Virginia where, on August 2, they sailed for Aquia Creek, and were transported from there two days later by rail to Fredericksburg, where they supported Union Army operation for roughly a week before being assigned to the Northern Virginia Campaign, during which they fought in the Battle of Cedar Mountain (August 9), engaged in operations at Kelly's Ford, White Sulphur Springs, Warrenton, and Manassas Junctions, and fought against the Confederate forces led by Stonewall Jackson in the Second Battle of Bull Run (August 28–30).According to historian Samuel P. Bates, Monaghan and his fellow 48th Pennsylvanians reached the battlefield at Bull Run at 1 p.m. on August 29 after “the action already having begun”, and were quickly positioned on the Union Army's far right