23rd Illinois Volunteer Infantry Regiment

23rd Regiment Illinois Volunteer Infantry "The First Irish"
Illinois state flag
Active	June 15, 1861, to July 24, 1865
Country	United States
Allegiance	Union
Branch	Infantry
Engagements	Battle of Lexington Relief of Clarksburg Relief of Parkersburg Relief of Moorefield Pursuit of Lee Hedgesville and Back Creek Kanawha Valley Hampshire and Hardy Counties, West Virginia Scout to Moorefield Raid on Baltimore and Ohio Railroad Sheridan's Shenandoah Valley Campaign Third Battle of Winchester Siege of Petersburg Assault on Ft Gregg-Fall of Petersburg Appomattox Campaign Surrender of the Army of Northern Virginia

The 23rd Regiment Illinois Volunteer Infantry, known as the "First Irish" or "Irish 'Brigade'", was an infantry regiment that served in the Union Army during the American Civil War.

The 23rd Illinois Infantry was organized at Chicago, Illinois and mustered into Federal service on June 15, 1861.

Initially assigned to garrison the town of Lexington, Missouri, the regiment surrendered to a much larger force of pro-secession Missouri State Guard commanded by State Guard Major General Sterling Price at the First Battle of Lexington in September 1861. After being paroled, General John C. Fremont (commanding the Department of Missouri) had the 23rd Illinois mustered out of service, but in December General George McClellan (now supreme commander in chief of all Union armies) had it restored.

After being reconstituted, the regiment left camp in the spring of 1862 for western Virginia, where it spent most of the rest of the war stationed there. In 1864, it joined General Philip Sheridan's army in the Valley Campaign. At the end of the year, the 23rd headed to the Richmond area for the Siege of Petersburg and was present at Appomattox.

The regiment was mustered out on July 24, 1865.

Organized at Chicago, Ill., and mustered in June 15, 1861. Moved to Quincy, Ill., July 14, thence to St. Louis, Mo., and to Jefferson City July 21, and duty there until September 8. March to Lexington September 8–11. Siege of Lexington September 12–20. Captured by Price September 20 and paroled. Regiment mustered out by order of General Fremont October 8, 1861, but restored by order of General McClellan, December 10, 1861. Reassembled at Chicago and guard prisoners at Camp Douglas until June 14, 1862. Moved to Harper's Ferry, West Va., June 14. Attached to R. R. District, Mountain Department, Harper's Ferry and New Creek to July, 1862. R. R. District, 8th Army Corps, Middle Department, to September, 1862. R. R. District West Va. to January, 1863. New Creek, Va., Defenses Upper Potomac, 8th Army Corps, Middle Department, to March, 1863. 5th Brigade, 1st Division, 8th Army Corps, to June, 1863. Mulligan's Brigade, Scammon's Division Dept. of West Virginia to December, 1863. 2nd Brigade, 2nd Division, West Virginia, to April, 1864. Kelly's Command, Reserve Division, West Virginia, to July, 1864. 1st Brigade, 3rd Infantry, Division West Virginia, to July, 1864. 3rd Brigade, 1st Infantry Division, West Virginia, to December, 1864. 2nd Brigade, Independent Division, 24th Army Corps, Army of the James, to June, 1865. 1st Brigade, Independent Division, 24th Army Corps, to July, 1865.