ADJUTANT-GENERAL'S OFFICE,

Des Moines, Iowa, January 13, 1862.

Brigadier-General THOMAS,

Adjutant-General U. S. Army, Washington:

GENERAL: Your letter of the 4th instant to His Excellency the Governor has been by him referred to me with direction to answer. In reply I have to state that Iowa has now in the field for three years or during the war, thirteen regiments of infantry, as follows:

Second Regiment Infantry, raised under second call of the President, as per telegram of War Department to Governor Kirkwood May 15 and letter May 16, 1861, 992 men. Third Regiment Infantry, raised under second call of the President, as per letter of War Department to Governor Kirkwood May 15 and letter May 16, 1861, 960 men. Fourth, Fifth, and Sixth Regiments Infantry, raised under authority Secretary of War by letter to Governor Kirkwood June 19, 1861; Fourth Regiment Infantry, 903 men; Fifth Regiment Infantry, 903 men; Sixth Regiment Infantry, 855 men. Seventh Regiment Infantry, raised under authority of War Department about June 29, 1861, 884 men. Eighth, Ninth, and Tenth Regiments Infantry, raised under authority of War Department, as per letter to Governor Kirkwood July 29, 1861; Eighth Regiment Infantry, 922 men; Ninth Regiment Infantry, 937 men; Tenth Regiment Infantry, 868 men. Eleventh Regiment Infantry, sanctioned by Secretary of War, as per letter to Governor Kirkwood October 7, 1861, 905 men. Twelfth Regiment Infantry, raised under authority of War Department by letter to Governor Kirkwood October 12, 1861, 914 men. Thirteenth Regiment Infantry, raised under authority of General Fremont, ratified by War Department as per letter to Governor Kirkwood October 7, 1861, 920 men. Fourteenth Regiment Infantry, raised under authority of General Fremont and ratified by War Department, as per letter to Governor Kirkwood October 7, 1861, 878 men. Three companies of this regiment are at Fort Randall.

In addition to the above regiments the Fifteenth Regiment Infantry, now forming at Keokuk, is nearly full, lacking about seventy-five men; raised under same order as Thirteenth. The Sixteenth Regiment Infantry, now forming at Davenport, has about 350 men and is gradually filling up; raised under authority of War Department by telegram November 12, 1861. The German regiment infantry has about 200 men. This regiment will probably be consolidated with the Sixteenth. Iowa has now in the field for three years, or during the war, three regiments cavalry, as follows: First Regiment Cavalry, raised under proclamation of the President May 3, 1861, and letters from War Department to the Governor under date June 19 and July 9, 1861, 1,043 men. Second Regiment Cavalry, raised under authority of War Department by letter to Governor Kirkwood July 29, 1861, 1,035 men. Third Regiment Cavalry, raised by authority of General Fremont and ratified by War Department, as per letter to Governor Kirkwood October 7, 1861, 1,088 men. Fourth Regiment Cavalry, raised by authority of War Department, by letters to Governor Kirkwood September 7 and October 12, 1861, 1,010 men. This regiment is full and mustered in, but have neither uniforms, arms, nor equipments. Iowa has also a cavalry company in the U. S. service called the Sioux City Cavalry, for frontier service, raised by authority of War Department, as per letter to Governor Kirkwood August 14, 1861, 91 men. This State has also three batteries of light artillery-one attached to Fourth Regiment Iowa Infantry, one attached to Ninth Regiment Iowa Infantry, and Fletcher's battery, now in Saint Louis.