Source: :
REPORT of the ADJUTANT GENERAL of the STATE OF INDIANA 1861-1865,
Volume 2, pages 309, 310.

31st Regiment, 3 Years Service, Indiana Volunteers

The Thirty-First Regiment was organized and mustered into service, for three years, at Terre Haute, on the 15th of September, 1861, with Charles Cruft as Colonel. Soon after it moved into Kentucky, and went into camp at Calhoun, on Green river, where it remained until a few days before the siege of Fort Donelson was commenced. Moving from Calhoun on the 11th of February, 1862, it reached the battle-field of Fort Donelson in time to participate in the engagement on the 13th and 14th, and was present at the surrender on the 15th of February: in this engagement it lost in killed twelve, wounded fifty-two, and missing four. Subsequently it marched to Fort Henry, and in the latter part of March was transported to Pittsburg Landing. In the battle of Shiloh it was actively engaged on both days, losing twenty-two killed, one hundred and ten wounded and ten missing. After this engagement it was assigned to the 4th division of the Army of the Ohio, commanded by General Nelson, and marching toward Corinth, participated in the siege of that place. After the siege was raised it moved with Buell's army through Northern Mississippi and Alabama into Tennessee, and until Buell's retreat to Louisville, Kentucky, it was stationed at various places in Middle Tennessee. Col. Cruft being appointed a Brigadier General on the 16th of July, 1862, Lieut. Col. John Osborn was commissioned his successor. In September the regiment fell back to Louisville with Buell's army, and after Bragg was driven out of Kentucky it returned to Nashville. Moving from that place in December, with Crittenden's Corps of Rosecran's army, it marched toward Murfreesboro and there participated in the battle of Stone River on the 31st of December, 1862, and 1st and 2d of January, 1863. In this engagement the Thirty-First lost five killed and forty-six wounded.

After the battle the regiment encamped at Cripple Creek, a short distance from Murfreesboro, where it remained guarding a mountain pass until June. It then moved forward with the army to Chattanooga, and on the 19th and 20th of September, was engaged in the battle of Chicamauga, losing four killed and sixty-six wounded. After the retreat to Chattanooga, the regiment crossed the Tennessee and encamped at Bridgeport, Alabama. While here the regiment re-enlisted as a veteran organization on the 1st of January, 1864, and in February proceeded to Indianapolis on veteran furlough. On Returning to the field in March, it was stationed at Ooltawah, Tennessee, and when the Atlanta campaign was commenced it moved forward with the 4th Corps, participating in the many skirmishes and battles that followed. After the Capture of Atlanta, the regiment moved northward with its corps in pursuit of Hood's army to Pulaski, Tennessee, and then fell back upon Nashville, after which it went as far as Huntsville, Alabama, in pursuit of the defeated army of Hood. Subsequently it moved into East Tennessee, and after a brief campaign in that section returned to Nashville, where it remained from the latter part of April until the middle of June, 1865. When the 4th Corps was transferred to New Orleans it moved with it, reaching that city early in July. Joining Gen. Sheridan's army at New Orleans it was transported to Texas, and marched into the interior of that State, forming part of the Army of Occupation. When this sketch was concluded (October, 1865,) the Thirty-First was still in service, and stationed at Green Lake, Texas.

Source:
REPORT of the ADJUTANT GENERAL of the STATE OF INDIANA 1861-1865,
Volume 3, pages xiv, ADDENDA AND ERRATA..