His pension says he was also in the Mexican War
The following from Ancestry.com
American Civil War Soldiers
about Abisha L Morrison
Name: Abisha L Morrison ,
Residence: Greencastle, Indiana
Enlistment Date: 30 August 1861
Distinguished Service: DISTINGUISHED SERVICE
Side Served: Union
State Served: Indiana
Unit Numbers: 577 577
Service Record: Enlisted as a Captain on 30 August 1861
Commission in Company A, 27th Infantry Regiment Indiana on 12 September 1861.
Transfered on 19 November 1861 from company A to company S
Promoted to Full Lieutenant Colonel on 19 November 1861 effective 19 November 1861
Resigned Company A, 27th Infantry Regiment Indiana on 11 January 1863

American Civil War Regiments
Regiment: 27th Infantry Regiment IN
Date Mustered: 04 November 1864
Regiment Type: Infantry
Enlisted Died of Disease or Accident: 10
Officers Died of Disease or Accident: 159
Enlisted Killed or Mortally Wounded: 2
Regimental Soldiers and History: List of Soldiers

Regimental History
Twenty-seventh Infantry INDIANA
(3 years)

Twenty-seventh Infantry. Col., Silas Colgrove; Lieut.-Cols.
Archibald T. Harrison, Abisha L. Morrison, John R. Fesler;
Majs., John Mehringer, William S. Johnson, George W. Burge,
Theodore F. Colgrove

This regiment was organized at Indianapolis in Aug. 1861, and
was mustered in Sept. 12. It left the state Sept. 15, for
Washington City where it was transferred to Banks' Army of the
Shenandoah in October.

It was in winter quarters near Frederick City, Md., and joined
the movement in Shenandoah Valley in March, 1862, marching
into Winchester on the 9th and after the battle of March 22-
23, joined in pursuit of Jackson's army. It was in the
battles of Front Royal and Winchester in May, holding back a
vastly superior force for nearly 4 hours, after which it fell
back with the army and engaged the enemy in the public
streets.

It became part of Banks' division of Pope's Army of Virginia
at Culpeper Court House and with that command participated in
the battle of Cedar Mountain. It then took part in the
Maryland campaign and was actively engaged at Antietam, where
it lost heavily. It was then placed on picket duty, on the
east bank of the Potomac, from Harper's Ferry to the mouth of
Opequan creek, and during the winter moved to the vicinity of
Fairfax Station, where it remained until spring.

It participated in the battle of Chancellorsville, losing
heavily, and in pursuit of Lee's invading army marched with
the 12th corps through Maryland into Pennsylvania, reaching
Gettysburg in time to take a prominent part in that battle,
and in the resistance to Pickett's charge on July 3, suffering
heavy loss.

It then joined in the pursuit of the retreating army to the
Potomac. In September it was transferred to the West with the
12th corps and was stationed at Tullahoma, Tenn., during the
fall and winter.

A portion of the regiment reenlisted on Jan. 24, 1864, and
after their return from furlough, it joined Sherman in
Georgia, participating in the battle of Resaca, where, on an
open field, it defeated the 32nd and 38th Ala., inflicting
heavy loss and taking the battle flag, colonel and 100
prisoners of the 38th. Its own loss was 68 killed and
wounded.

It participated in all the marching and skirmishing, battles and assaults of the army in the Atlanta campaign, moving to the city at its conclusion. The non-veterans were mustered out Nov. 4, 1864, the veterans and remaining recruits being transferred to the 70th regiment, and serving with it through the campaign to Savannah and up through the Carolinas.

On the muster-out of the regiment they were transferred to the
33rd, with which they served until its muster out at
Louisville, July 21, 1865. The original strength was 1,052;
gain by recruits, 116; reenlistments, 154; total, 1,322. Loss
by death, 275; desertion, 47; unaccounted for, 52.

Source: The Union Army, vol. 3

Battles Fought

Fought at Cheat Mountain, WV.
Fought on 15 January 1862 at Mississippi Flotilla.
Fought on 24 May 1862 at Winchester, VA.
Fought on 09 August 1862 at Cedar Mountain, VA.
Fought on 17 September 1862 at Antietam, MD.
Fought on 03 May 1863 at Chancellorsville, VA.
Fought on 03 July 1863 at Gettysburg, PA.
Fought on 15 May 1864 at Resaca, GA.
Fought on 20 July 1864 at Peach Tree Creek, GA