Commanding Officer on the Antietam Campaign:
John F. Reynolds
This Brigade's Chain of Command:
Corps - Middle Department (8th Army Corps)
"On the 4th of September, Governor Curtin issued a proclamation, calling on the people to arm, and prepare for defense. He recommended the immediate formation of companies and regiments throughout the Commonwealth, and, for the purpose of drill and instruction, that after three P. M., of each day, all business houses be closed. On the 10th, the danger having become imminent, the enemy being already in Maryland, he issued a general order, calling on all able bodied men to enroll immediately for the defense of the State, and to hold themselves in readiness to march upon an hour's notice; to select officers, to provide themselves with such arms as could be obtained, with sixty rounds of ammunition to the man, tendering arms to such as had none, and promising that they should be held for service, for such time only as the pressing exigency for State defense should continue."
"On the following day, acting under authority of the President of the United States, the Governor called for fifty thousand men, directing them to report by telegraph for orders to move, and adding that further calls would be made as the exigencies should require. The people everywhere flew to arms, and moved promptly to the State Capital. One regiment and eight companies were sent forward during the night of the 12th, and others followed as fast as they could be organized. On the 14th, the head of the Army of the Potomac met the enemy at South Mountain, and hurled him back through its passes, and on the evening of the 16th, and day of the 17th, a fierce battle was fought at Antietam."
"In the meantime, the militia had rapidly concentrated at Hagerstown and Chambersburg, and General John F. Reynolds, who was at the time commanding a corps in the Army of the Potomac, had assumed command. Fifteen thousand men were pushed forward to Hagerstown and Boonsboro, and a portion of them stood in line of battle in close proximity to the field, in readiness to advance, while the fierce fighting was in progress. Ten thousand more were posted in the vicinity of Greencastle and Chambersburg and
'about twenty five thousand,' says Governor Curtin, in his annual message, ''were at Harrisburg, on their way to Harrisburg, or in readiness and waiting for transportation to proceed thither.' "
1 Bates' text transcribed online by Alice Gayley. See, also, her listing of all units with rosters.
Bates, Samuel Penniman, History of the Pennsylvania Volunteers, 1861-65, Harrisburg: State of Pennsylvania, 1868-1871 [AotW citation 487]