The 4th Iowa Cavalry was organized at Camp Harlan in Mount Pleasant, Iowa, beginning in September 1861, and mustered in for three years service under the command of Colonel Asbury B. Porter.

District of Eastern Arkansas, Department of Missouri, to December 1862.

2nd Brigade, 1st Cavalry Division, District of Eastern Arkansas, Department of the Tennessee, to January 1863.

2nd Brigade, 2nd Cavalry Division, XIII Corps, Department of the Tennessee, to May 1863.

Unattached, XV Corps, Army of the Tennessee, to August 1863.

2nd Brigade, 1st Cavalry Division, XVI Corps, to July 1864.

2nd Brigade, 2nd Cavalry Division, District of West Tennessee, to November 1864.

2nd Brigade, Cavalry Division, District of West Tennessee, to February 1865.

Ordered to Rolla, Mo., March 10; thence to Springfield, Mo., and duty there until April 14.

Skirmish at Nitre Cave, White River, April 18 (Companies G and K).

Talbot's Farm, White River, April 19 (Companies E, F, G, and K).

(Company F detached for duty with Chief Commissary and as provost guard at Helena, Ark., May 1862 to April 1863.)

Jones' Lane or Lick Creek October 11 (Companies A, G, and H).

(Company G detached on courier duty at Young's Point, La., during May.)

Engaged in outpost duty against Johnston between Big Black and Yazoo Rivers.

Expedition from Haines Bluff to Satartia and Mechanicsville June 2–8 (detachment).

Bear Creek or Jones' Plantation June 22 (Companies A, F, I, and K).

Big Black River, near Birdsong Ferry, June 22 (detachment).

Messenger's Ferry, Big Black River, June 26.

Raid from Big Black on Mississippi Central Railroad and to Memphis, Tenn., August 10–22.

Raymond Road, Edwards Ferry, Champion Hill, Baker's Creek and near Bolton's Depot February 4.

(Forrest's attack on Memphis August 21, Company G.) Moved to Little Rock, Ark., September 2–9.

; thence to Cape Girardeau, St. Louis, Jefferson City and Independence, Mo.. Trading Post and Fort Scott, Kansas, Pea Ridge and Fayetteville, Ark., Tahlequah and Webber's Falls, Indian Territory, returning via Pea Ridge, Springfield and Rolla to St. Louis.

Westport, Big Blue and State Line October 23.

Marias Des Cygnes, Osage, Mine Creek October 25.

Skirmish on Germantown Pike, near Memphis, December 14, detachments of Companies A and B. Grierson's Raid on Mobile & Ohio Railroad December 21, 1864, to January 5, 1865.

Dismounted men of the regiment moved from Memphis, Tenn., to Louisville, Ky., January 2, 1865.

Moved to Gravelly Springs, Ala., February 1865, and duty there until March 20.

Company G served as escort to General Emory Upton, Commanding Division.