Organized at Benton Barracks, Mo., as Birge's Western Sharpshooters under authority of General Fremont, September and October, 1861. Mustered in as 14th Missouri Infantry November 23, 1861, Attached to Dept. of Missouri to February, 1862. 1st Brigade, 2nd Division, District of West Tennessee, February, 1862. 4th Brigade, 2nd Division, District West Tennessee, to March, 1862. 2nd Brigade, 2nd Division, Army of the Tennessee to July, 1862. 2nd Brigade, 2nd Division, District of Corinth, Miss., to November, 1862. Unattached, District of Corinth, Miss., 13th Army Corps (Old), Dept. of the Tennessee, to December, 1862. Unattached, District of Corinth, 17th Army Corps, to January, 1863. Unattached, District of Corinth, 16th Army Corps, to March, 1863. Unattached, 2nd Division, 16th Army Corps, to November, 1863. 2nd Brigade, 2nd Division, 16th Army Corps, to September, 1864. 2nd Brigade, 4th Division, 15th Army Corps, to April, 1865. 3rd Brigade, 1st Division, 15th Army Corps, to July, 1865.
SERVICE - Moved to Centralia, Mo., December 12 - 14, 1861. Operating against Bushwhackers of Price's Army, December 14 - 28. Silver Creek December 25. Capture of Columbia December 26. Mt. Zion Church December 28. Moved to Sturgeon, Mo., December 29. Duty there and scouting about Renick, Macon and Centralia till February, 1862. Moved to St. Louis, Mo., thence to Cairo, Ill., Paducah, Ky., and Fort Henry, Tenn., February 4 - 9. Investment and capture of Fort Donelson, Tenn., February 12-16. Moved to Savannah, thence to Pittsburg Landing, Tenn., March 5 - 17. Battle of Shiloh, Tenn., April 6 - 7. Advance on and siege of Corinth, Miss., April 29 - May 30. Phillips' Creek May 21. Occupation of Corinth May 30. Pursuit to Booneville June 1 - 8. Duty at headquarters General Grant, Corinth, Miss., till August 25. Expedition to Bethel, Tenn., August 28 - 30. Burnsville September 17. March to Glendale and Iuka September 18 - 21. Battle of Iuka September 19. Battle of Corinth, Miss., October 3 - 4. Pursuit to Hatchie River October 5 - 12. Skirmish at Hatchie River October 9. Scout to Hatchie River November 2 - 5. At Rienzi till November 26. Moved to the Tuscumbia Hills and established Camp Davies, and duty there till November, 1863. Designation of Regiment changed to 66th Illinois Infantry November 20, 1862. Skirmishes at Tuscumbia Bridge December 19, 1862. Danville December 20. Hatchie River December 30. Rienzi January 7, 1863. Danville, Tuscumbia Bridge and Rienzi January 24 - 25. Danville February 8. Ripley Cross Roads March 25. Booneville April 1. Glendale April 14. Jumpertown May 12. Kossuth May 24. Cartersville June 6. Yellow Creek June 8. Seward House and Jumpertown July 11. Jacinto August 9. Rienzi August 11. Seward House August 19. Whitesides Farm September 9. Relieved at Camp Davies November 1, and march to Pulaski, Tenn., November 1 - 12. Duty there till April 29, 1864. Veterans on furlough January 16 - March 8. Atlanta Campaign May 1 to September 8. Demonstrations on Resaca May 8 - 13. Snake Creek Gap and Sugar Valley, near Resaca, May 9. Near Resaca May 13. Battle of Resaca May 14 - 15. Ley's Ferry, Ostenaula River, May 14 - 15. Rome Cross Roads May 16. Advance on Dallas May 18 - 25. Operations on line of Pumpkin Vine Creek and battles about Dallas, New Hope Church and Allatoona Hills May 25 - June 5. Operations about Marietta and against Kenesaw Mountain June 10 - July 2. Assault on Kenesaw June 27. Nickajack Creek July 2 - 5. Ruff's Mills July 8 - 4. Chattahoochie River July 6 - 17. Decatur July 20-21. Battle of Atlanta July 22. Siege of Atlanta July 22 - August 25. Non-Veterans mustered out August 26, 1864. Flank movement on Jonesboro August 25 - 30. Battle of Jonesboro August 31 - September 1. Lovejoy Station September 2 - 6. Moved to Rome, Ga., September 26, and duty there till November 10. Reconnaissance from Rome on Cave Springs Road and skirmishes October 12 - 13. March to the sea November 15 - December 10. Waynesboro November 27 - 28. Wrightstown November 29. Ogeechee Canal and Wilmington Cross Roads December 9. Siege of Savannah December 10 - 21. Campaign of the Carolinas January to April, 1865. Salkehatchie Swamp, S.C., February 2 - 5. South Edisto River February 9. North Edisto River February 11 - 12. Columbia February 15 - 17. Camden February 24. Battle of Bentonville, N. C., March 20-21. Occupation of Goldsboro March 24. Advance on Raleigh April 10 - 14. Occupation of Raleigh April 14. Bennett's House April 26. Surrender of Johnston and his army. March to Washington, D.C., via Richmond, Va., April 29 - May 19. Grand Review May 24. Moved to Louisvi1Ie, Ky., June 3 - 8.
Mustered out July 7, 1865.
Regiment lost during service 6 Officers and 73 Enlisted men killed and mortally wounded and 2 Officers and 146 Enlisted men by disease. Total 227.