As a part of Gen. Sherman’s army, the regiment was then advanced against the Rebels under Price, strongly intrenched on the Tallahatchie river on the railroad below Waterford, Mississippi.  Gen. Grant’s army was at the same time moving down the railroad, with base of supplies at Holly Springs.  The enemy retreating from the Tallahatchie, the Twenty-seventh was soon assigned to guarding railroad on the river.  In the meantime, Holly Springs was lost to us, and Gen. Grant’s expedition, with Vicksburg for its object, was abruptly brought to a close.  December 31st, the regiment, except Company G, serving as a train guard, was sent with re-enforcements to Gen. Sullivan, operating against the Rebels under Gen. Forrest near Lexington, Tennessee.  But Forrest was defeated that same day by the victory of Parker’s Cross Roads, where the Thirty-ninth Iowa fought so nobly.  The Twenty-seventh joined in the pursuit.  At the close of the year 1862, the Twenty-seventh had lost 69 enlisted men.  Nearly 200 more were lying in hospitals in seven different states.

Until June 2, 1863, the regiment was at Jackson, Tennessee, performing provost, guard and picket duties.  There were a number of marches into the country.  One was to Corinth, where the regiment remained twenty days, while the troops, previously there under Gen. Dodge, made a successful raid to Tuscumbia, Alabama.  A detachment of the regiment went once as train guard to Burnsville, Mississippi.  From February 3d to the 28th, five companies were at Henderson Station as railroad guard.  May 6th the companies were all distributed at various stations between Corinth and Memphis.  Early in June, Jackson was evacuated, when the regiment moved to Moscow, again guarding railway.  June 6th, Lt.-Col. Lake was made commandant of the post at La Grange.  Maj. Harvard [probable misprint - s/b Howard] took command of the regiment and until August 15th, Col. Gilbert of the brigade.  August 20th, the regiment marched for Memphis.

The next expedition was to Arkansas.  At Brownsville the brigade joined the Army of Arkansas under Gen. Steele.  This army captured Little Rock, September 10, 1863.  The battery of the brigade was engaged, the infantry being in reserve.  The regiment started November 15th for Memphis, reporting to Gen. Hurlbut of the Sixteenth army corps.  Here it did picket duty the remainder of the year 1863.

January 28, 1864, the regiment moved to Vicksburg.  In the brigade of Col. Shaw of the 14th Iowa, together with the Fourteenth and Thirty-second Iowa, and Twenty-fourth Missouri, it participated in Gen. Sherman’s Meridian raid.  March 10th, with this gallant command, it embarked under Gen. A. J. Smith for Gen. Bank’s Red River campaign.  Approaching Fort de Russey, the regiment was doing as provost guard in Marksville, until the army should pass.  Accomplishing this it moved rapidly after the column, Col. Gilbert hurrying word forward, that if a battle were in prospect, the Twenty-seventh wished to be in it.  Permission being accorded, the regiment joined in the charge, crossing the field, springing into the ditch, mounting the parapet and compelling surrender.  Again at the hot battle of Pleasant Hill on April 9th, the Twenty-seventh bore an active and gallant part, suffering severe loss.  Col. Gilbert was among the wounded.  With it’s brave brigade it did the hardest fighting of the day.  Covering the army on the grand retreat, there was continuous skirmishing and fighting.  May 18th, occurred the battle of Yellow Bayou or Old Oaks, where Shaw’s brigade was actively engaged.  "It saved the army," said Col. Shaw.  The Twenty-seventh lost 3 killed and 14 wounded.  Among the latter was Capt. Chas. A. Slocum.  The command arrived at Vicksburg May 24th.  June 4th, it embarked for Memphis, but on the 5th debarked to dislodge the enemy at Ditch Bayou on Old River Lake, Chicot county, Arkansas.  Col. Gilbert led the brigade and Maj. Howard the regiment.  Routing the enemy, the command moved to Memphis.

Next, the regiment was engaged in the expedition under A. J. Smith to Tupelo, Miss.  In the battles of Tupelo and Old Town Creek, it was an active participant.  In August, the regiment was in the Oxford expedition of Gen. Smith, returning to Memphis August 30th.  September 5th, it was ordered to Missouri, where in October, in the army of Gen. A. J. Smith, it joined in the pursuit of Price, returning to St. Louis November 18th.  November 25th, still in Gen. Smith’s army, the regiment moved to Nashville, Tenn., debarking December 1st.  In the battle of Nashville, December 15th and 16th, the regiment participated.  It was led by Lt.-Col. Lake.  Col. Gilbert commanded the brigade, which was conspicuous for bravery.  He was promoted brigadier general for gallantry.  December 17th, the regiment joined in the pursuit of the enemy.  January 5th, 1865, found the regiment at Eastport, Miss.  On the 9th, it made a reconnaissance to Iuka.  February 9th, it left to enter on the Mobile campaign.  Leaving Dauphin Island on March 20th, on the 25th, with its command, it joined in the march with the Thirteenth and Sixteenth army corps, arriving near Mobile on the 26th.  April 3d, the march was resumed to Blakely.  The regiment engaged with honor in the siege and in the assault.  It was led by Maj. Howard.  With its brigade, under Gen. Gilbert, it occupied Blakely on the 10th.  On the 13th, it marched for Montgomery.

July 14th, 122 recruits, whose terms of service would expire later than October 1, 1865, were transferred from the Twenty-seventh Iowa to the Twelfth Iowa Infantry.  After this, however, delayed until August 8, 1865, when it was finally mustered out at Clinton, Iowa.  Its record had been one of constant bravery and constant fidelity to the cause it had served.

Col. Gilbert was made brigadier general February 9, 1865, and was brevetted major general March 26th, for gallantry at Blakely.