The regiment was assigned to patrol and outpost duty on the Upper Potomac until March, 1862. It first saw action at Beller's Mill, near Harper's Ferry, West Virginia, on September 2, 1861. Pritchard's Mills September 18 (2 Cos.). Bolivar Heights near Harper's Ferry, October 16. (Cos. "C," "D," "I" and "K" detached at Hancock, Md., January 5–30, 1862.) Occupation of Winchester, Virginia, March 12. Pursuit of Jackson up the Shenandoah Valley from March 24 to April 27. Guard duty on the Orange &amp; Alexandria Railroad May 3 to 18. Battle of Cedar Mountain on August 9. Pope's Campaign in Northern Virginia August 16 to September 2. Battle of Thoroughfare Gap on August 28. 2nd Battle of Bull Run on August 30. Battle of Chantilly September 1. Served in the Maryland Campaign September to October. Battles of South Mountain September 14, and the Battle of Antietam September 16–17. At Sharpsburg until October 30. Movement to Warrenton, thence to Falmouth, Virginia, October 30 to November 19. Fought at the Battle of Fredericksburg, Virginia, from December 12 to 15.