On September 1st, 1862, after the disaster affectionately known as "2nd Bull Run," the 55th Ohio was stationed in the works outside of Centerville,
Virginia. The 55th's Division Commander, General Robert C. Schenck, was critically wounded just days before during the battle, so he was replaced by
Brigadier-General Julius Stahel. At midnight the 55th Ohio with other troops was moved to Arlington Heights across from Washington. It was soon moved to Munson's Hill and encamped there for several days.General John Pope's former "Army of Virginia" was officially merged into the Army of the Potomac commanded by Major-General George McClellan. General Sigel's command was officially named the 11th Corps with the 55th Ohio now in the 2nd Brigade (McClean), 1st Division (Stahel). While the rest of the Army went upon the campaign that would culminate in the battle of Antietam, the 11th Corps was left behind in Washington for guard duty.
On September 25th, McClean's brigade was sent on a reconnaissance from Centerville towards Bristoe Station and Warrenton. The brigade encamped at Weiss House that evening about one mile near Manassas Junction. The next morning, the brigade marched to Bristoe Station to await elements of the 6th Ohio Cavalry who arrived at 11:00 a.m. Shortly the cavalry ran off some enemy cavalry that were observing the column. Within a couple of miles at Catlett's Station enemy cavalry and infantry were encountered. The 75th Ohio was sent forward as skirmishers with the 73rd and 55th Ohio's in support in full battle lines. The rebels fled into town and escaped via train before McClean's men could catch them. The brigade did, however, save the bridge that the Johnny's had tried to burn.
On the 27th of September, the brigade marched back to Bristoe Station and the next day was sent back to Centerville.
Sources:
Trials and Triumphs: A Record of the Fifty-Fifth Ohio Volunteer Infantry by
Hartwell Osborne, 1904, A.C. Clurg & Co., Chicago.
All Brave And True by Dan Munson, 1987.