18th Regiment, Lieutenant-Colonel J. J. Sears.—Organized in the State of Missouri February, 1864. Battles: Nashville, December 7th, 15th, and 16th, 1864, Sand Mountain. Mustered out February, 1866.
19th Regiment, Colonel Joseph G. Perkins.—Organized at Camp Staunton, Md., December, 1863. Battles: Petersburg, Bermuda Hundreds, November 30th, December 4th, 1864. Mustered out January, 1867.
20th Regiment, Colonel Nelson B. Bertram.—Organized at Piker's Island, N. Y., February, 1864. Mustered out October, 1865.
21st Regiment, Colonel Augustus G. Bennett. Organized at Hilton Head, S. C., Fernandina, Fla., June, 1863, as the 3d and 4th South Carolina. Consolidated March, 1864, and designated as the 21st U. S. Regiment. Mustered out April, 1866.
22d Regiment, Colonel Joseph B. Kiddoo. Organized at Philadelphia, Pa., January, 1864. Battles: Petersburg, New Market Heights, Dutch Gap, Chapin's Farm, September 29th, November 4th, 1864, Fair Oaks. Mustered out 1865.
23d Regiment, Lieutenant-Colonel Marshall L. Dempey. Organized at Camp Casey, Va., November, 1863. Battles: Petersburg, Bermuda Hundreds. Mustered out November, 1865.
24th Regiment, Colonel Orlando Brown.—Organized at Camp William Penn, Pa., January, 1865—one year. Company F mustered out September, 1865; remaining companies October, 1865.
25th Regiment, Colonel F. L. Hitchcock.—Organized at Philadelphia, Pa., January, 1864. Mustered out December, 1865.
26th Regiment, Colonel William B. Guernsey.—Organized at Piker's Island, N. Y., February, 1864. Battles: John's Island, July 5th and 7th, McKay's Point, Gregory's Farm.
27th Regiment, Lieutenant-Colonel John W. Dounellon.—Organized at Camp Delaware, Ohio, January, 1864. Battles: Petersburg, Hatcher's Run. Mustered out November, 1865.