This regiment was raised chiefly in the counties of Henry, Fremont, Delaware, Buchanan, Poweshiek, Wapello, Mahaska, Lee, Chickasaw, Bremer, Mitchell, Madison and Jefferson. They were mustered into the service in November, 1861, and numbered 1,036. The field officers were: Colonel, Asbury B. Porter; lieutenant-colonel, Thomas Drummond; majors, Simeon D. Swan, Joseph E. Jewett and George A. Stone. In February, 1862, the regiment was ordered to St. Louis and was sent from there to southwestern Missouri. In April it joined General Curtis' army and afterwards went to Helena, where it remained until April, 1863. In October Major Rector, with fifty men of the regiment, was defeated and captured with fourteen of his men. In May the regiment joined Grant's army in the Vicksburg campaign and did good service in the capture of the city. Colonel Porter resigned and Major Winslow was commissioned in his place. The Fourth was engaged in several raids in the enemy's country and had some sharp fights with slight loss. It was in the Meridian campaign and had frequent skirmishes with the rebels. In March, 1864, the veterans of the regiment who had re-enlisted went home on furlough. The regiment received enough recruits to bring its number up to 1,354 in May, 1864.
In June General Sturgis led an army of 12,000 men against the rebel army under Forrest. Colonel Winslow commanded a brigade of cavalry composed of the Third and Fourth Iowa and the Tenth Missouri. Through the utter incompetency of General Sturgis, his army was beaten at Guntown, his wagon train and artillery captured and his disorganized infantry driven in a vast mob of fleeing men back to Memphis. Colonel Winslow commanded the rear guard in the disastrous flight and with his cavalry made a gallant resistance and saved the army from total destruction. Sturgis' loss of men was about 4,000, most of whom were captured. The Fourth also participated in the battle of Tupelo, where Gen. A. J. Smith, with 12,000 men, defeated General Forrest with 14,000. In September Winslow's brigade of cavalry joined in General Smith's pursuit of General Price's army in Missouri and fought bravely in several battles, in one of which Colonel Winslow was severely wounded. In this campaign the Fourth Iowa had marched more than 2,000 miles and worn out two sets of horses.
Colonel Winslow was promoted to brigadier-general and Lieutenant Colonel Peters was in command of the Fourth cavalry. The regiment was with General Wilson in his campaign through Alabama in March and April, 1865, in which the Fourth fought in several battles and captured more than 900 prisoners. In August, 1865, this regiment, after its brilliant career, was mustered out and discharged at Davenport.
SOURCE: Benjamin F. Gue, Biographies And Portraits Of The Progressive Men Of Iowa, Volume 1, p. 121-2