Organized at Chicago, Ills., October, 1861. Assigned to 12th Illinois Cavalry as Companies "H" and "I," February, 1862, but served detached until February, 1863. Attached to Stoneman's Cavalry Command, Army of the Potomac, to March, 1862. Blake's Brigade, Cavalry Reserve, Army of the Potomac, to April, 1862. Headquarters Army Potomac to November, 1862. Provost Guard Army of the Potomac to February, 1863, and at Headquarters 3rd and 2nd Divisions Cavalry Corps, Army Potomac, to November, 1863, participating in the following service: Duty in the Defenses of Washington, D.C., until March, 1862. Moved to the Peninsula, Virginia. Peninsula Campaign, April to August. Siege of Yorktown, Va., April 5-May 4. Near Williamsburg May 4. Battle of Williamsburg May 5. Reconnaissance to Hanover Court House May 26. Seven days before Richmond June 25-July 1. Battles of Mechanicsville June 26. Gaines' Mill June 27. Peach Orchard and Savage Station June 29. White Oak Swamp and Glendale June 30. Malvern Hill July 1. Campaign in Northern Virginia August 27-September 2. Maryland Campaign September-October. Battle of Antietam September 16-17. Movement to Falmouth, Va., October 29-November 17. Battle of Fredericksburg, Va., December 12-15. "Mud March," January 20-24, 1863. Chancellorsville Campaign April 27-May 6. Stoneman's Raid April 29-May 8. Brandy Station and Beverly Ford June 9. Upperville June 21. Battle of Gettysburg, Pa., July 1-3. Williamsport, Md., July 6. Boonsboro July 8. Benevola or Beaver Creek July 9. At and near Funkstown July 10-13. Falling Waters July 14. Chester Gap July 26. Kelly's Ford July 3-August 1. Brandy Station August 1-4 and September 7-8. Bristoe Station September 12. Culpeper Court House September 13. Raccoon Ford September 14-16. Stevensburg September 17. Jack's Shop, Madison Court House, September 22. Bristoe Campaign October 9-22. Raccoon and Morton's Fords, October 10. Brandy Station October 11-12. Oak Hill October 15. Rejoined regiment and moved to Chicago, Ills., November 20-28, 1863. See 12th Illinois Cavalry.