1861 September 9
The 105th Regiment of Pennsylvania Volunteers is organized under the authority of Colonel Amor A. McKnight in Pittsburgh, Pennsylvania. Soldiers are recruited largely from Jefferson County, thus acquiring the nickname "Wild Cat Regiment." Upon organization, the men march to Washington, D.C., where they receive their supplies.
By order of General McClellan, the regiment crosses the Potomac River into Virginia and sets up Camp Jameson on the property of George Mason. For the next six months the soldiers participate in training drills in their winter quarters. Elections of officers are held during this period, and the regiment is assigned to the First Brigade of General Heintzelman's First Division, Third Army Corps.
1862 March 17
As part of the Army of the Potomac's Peninsular Campaign, the 105th steams down to Fortress Monroe and camps near the village of Hampton, Virginia.
The regiment leaves camp and heads to Yorktown, camping about two miles south of the city. The soldiers' primary work is building roads for the passage of artillery or doing picket duty.
After the Confederate evacuation of Yorktown, the 105th begins to march towards Williamsburg. The next day, three companies are used as skirmishers to enter the town. The regiment remains in the vicinity for several days and then begins to march along the Chickahominy River in the direction of Richmond.
The 105th takes part in the Battle of Fair Oaks.
The regiment takes part in the Battle of Charles City Cross-Roads.
The regiment takes part in the Battle of Malvern Hill.
July 2-August 14
The 105th remains in camp at Harrison's Landing on the James River.
Now detailed in Pope's Campaign, the regiment moves from Harrison's Landing to guard duty on the railroad from Manassas to Catlett's Station.
The 105th fights at Bristow Station.
The 105th participates in the Battle of Second Bull Run.
The regiment takes part in the Battle of Chantilly. It spends the remainder of the month as part of General Heintzelman's forces guarding Washington.
The 105th departs from Washington to march and perform picket duty between Poolesville, Maryland, and Falmouth, Virginia, near Fredericksburg.
November 22-December 10
The regiment sets up camp in Falmouth.
Based on Kate M. Scott's History of the One Hundred And Fifth Regiment of Pennsylvania Volunteers (Philadelphia: New-World Publishing Co., 1877).