I didn't think about it the other day when I was doing this but there was another Isaac Tice - this from NY:

Is it possible that when he resigned from the 48th Ohio Inf, say for health reasons, he went back to New York to recover and in Sept 1864 chose to go back to war but this time with a New York unit? Could he have been one of the 18 who died?

American Civil War Soldiers
Name: Isaac Tice
Enlistment Date: 3 Sep 1864
Enlistment Place: Norwich, New York
Side Served: Union
State Served: New York
Service Record: Enlisted as a Private on 3 September 1864 at the age of 26 [b. abt 1838].
Enlisted in 3rd Light Artillery Regiment New York on 3 Sep 1864.
REGIMENT: 3rd Light Artillery Battery New York
Date of Organization: 17 Jun 1861
Muster Date: 24 Jun 1865
Regiment State: New York
Regiment Type: Light Artillery
Regiment Number: 3rd
Enlisted Died of Disease or Accident: 0
Officers Died of Disease or Accident: 0
Enlisted Killed or Mortally Wounded: 14
Enlisted Died of Disease or Accident: 4

Regimental History
New York
THIRD INDEPENDENT BATTERY, LIGHT ARTILLERY (VETERAN).
(Three Years)
This battery was originally Company D--the howitzer
company--of the 2d Militia, later 82d Infantry. It served
detached from its regiment, and was known as Battery B, N. Y.
Volunteer Artillery, until, December 7, 1861, it received its
numerical designation from the State. It was recruited and
organized in New York city and left the State, commanded by
Capt. Thaddeus P. Mott, May 19, 1861. It was mustered in the
service of the United States for three years, June 17, 1861, at
Washington, D. C., and shortly thereafter detached from its
regiment and converted into a light battery. At the expiration
of its term of service the men entitled thereto were
discharged, and the battery continued in service. It served at
and near Washington, D. C., from May, 1861; in W. T. Smith's
Brigade, Division Potomac, from August 4, 1861; in Hancock's
Brigade, Smith's Division, Army of the Potomac, from October,
1861; in same brigade and division, 4th Corps, from March,
1862; in 2d Division, 6th Corps, from May, 1862; in 1st
Division, 4th Corps, from September 15, 1862; in 3d Division,
6th Corps, from October, 1862; in the 2d Division, 6th Corps,
from November, 1862; with the Light Division, 6th Corps, from
April, 1863; in the Artillery Brigade, 6th Corps, from May,
1863; in the Artillery Reserve, Army of the Potomac, from July
10, 1864; in the Artillery Brigade, 6th Corps, from December,
1864, and June 24, 1865, commanded by Capt. W. A. Harn, it was
honorably discharged and mustered out at New York city.

Source: The Union Army, vol. 2

Gettysburg after battle report:

Report of Capt. William A. Harn, Third New York Battery.

----, --- ---, 1863.
Sir: Started from Stafford Heights at daylight of the 14th June;
halted at Stafford Court-House for a rest; started again about 10 p. m.

June 15.--Halted at Dumfries, and went into camp.

June 16.--On the road again about 2.30 a. m.; halted near Fairfax
Station, Va.; very dusty traveling.

June 17.--In camp near Fairfax Station.

June 18.--Marched from camp near the station about 7 a. m.;
passed through Fairfax, and went into camp about half a mile from
the village.

June 19.--In camp near Fairfax; raining very hard.

June 20.--Still in camp; Lieut. Harn received his commission
as captain

June 21, 22, 23.--Still in camp near Fairfax.

June 24.--Left camp near Fairfax about 3 p. m.; arrived at camp
near Centreville about 5 p. m.

June 25.--Shifted camp; battery in camp on the heights of Centreville.

June 26.--Marched from Centreville to Dranesville.

June 27.--Marched from camp near Dranesville about 4 a. m.;
crossed the Potomac at Edwards Ferry, and went into camp for the
night near Poolesville, Md.

June 28.--On the march; about 4 a. m. passed through Barnesville
and Hyattstown; encamped in the field.

June 29.--On the road again at 4 a. m.; battery halted at New
Market, bringing up the rear of the column; reached camp at midnight.

June 30.--Marched again about 6 a. m.; passed through Westminster,
halted, and went into camp about 2 miles from Manchester.

July 1.--In camp near Manchester; started about 8 p. m.; passed
through Littlestown, Pa., about noon of the 2d of July.

July 2.--Encamped near the battle-field of Gettysburg, Pa.

July 3.--In camp, awaiting orders; battery hitched up. Battery
ordered in front; went into position.

July 4.--Moved from position to the rear; battery still hitched
up, waiting orders.

July 5.--Marched about 6 a. m.; opened fire on the rear guard of
the enemy about 8 a. m. with one section of the battery. Limbered
up, and again took position, keeping within supporting distance of
the skirmishers, until our advance was checked by the rear guard of
the enemy, which was supported by artillery. The battery moved
quickly to the front, and took up position on the heights overlooking
the town of Fairfield, and opened fire on the enemy, driving him from
his position. Battery remained in position all night.

July 6.--Marched at 4 p. m.; passed through Fairfield; battery in
park outside the town. Started again about dusk; passed through
Emmitsburg about midnight; went into camp.

July 7.--Started about 7 a. m. in the direction of Middletown;
marched all day; took the wrong road; reversed limbers, and remained
in the road all night.

July 8.--Started about daylight; proceeded over the mountain in
the direction of Middletown; encamped about 1 1/2 miles from the
town.

July 9.--Marched about noon; passed through Middletown and
Boonsborough; battery in position outside the town.

July 10.--Started about 5 a. m. in advance of the Vermont Brigade,
supporting the cavalry and horse artillery of Gen. Buford, driving
the enemy in the direction of Funkstown, where we found him
in strong position. Battery took up position, supporting the Vermont
Brigade. Occasional firing during the day.

July 11.--Same position as the preceding day.

July 12.--Passed through Funkstown; went into position; limbered
up, and went into camp about 7 p. m.

July 13.--Battery hitched up all day.

July 14.--Marched in the direction of Williamsport; encamped near
the town.

July 15.--Marched through Hagerstown, Funkstown, and Boonsborough;
encamped near the town.

July 16.--Marched about 4 a. m.; passed through Middletown;
went into camp near Berlin about 5 p. m.

July 17.--In camp near Berlin; raining.

July 18.--Same as preceding day.

July 19.--Marched about 7 a. m.; crossed the Potomac at Berlin,
Md.; passed through Lovettsville, Va.; went into camp about 5 p. m.

July 20.--Marched all day; went into camp at 7 p. m.

July 21.--Shifted camp.

July 22.--Marched from camp in the field about 10 a. m.; went
into camp about 6 p. m., near Goose Creek.

July 23.--Started at daylight; arrived about 8 a. m. at Snickersville;
left again about 10 a. m.; passed through Salem, and went into
camp about 11 p. m.

July 24.--Left camp at 6 o'clock, and marched in the direction of
Manassas Gap; battery halted for two hours or thereabouts; proceeded
in the direction of Orleans; battery in camp about 8 p. m.

July 25.--Marched at 7 a. m.; passed through Orleans; went into
camp about 1 mile from Warrenton at 5 p. m.

W. A. HARN,
Capt., Comdg. Third New York Battery.

Col. C. H. Tompkins,
Comdg. Artillery Brigade.

Source: Official Records: Series I. Vol. 27. Part I. Reports. Serial No. 43

Battles Fought
Fought on 21 Jul 1861 at Bull Run, VA.
Fought on 25 Jan 1862 at Fairfax County, VA.
Fought on 16 Apr 1862 at Lee's Mills, VA.
Fought on 30 Jun 1862 at White Oak Swamp, VA.
Fought on 1 Jul 1862 at White Oak Swamp, VA.
Fought on 13 Feb 1863.
Fought on 24 Jul 1863 at White Plains, VA.
Fought on 27 Jul 1863.
Fought on 12 May 1864 at Spotsylvania Court House, VA.
Fought on 24 May 1864.
Fought on 31 May 1864 at Cold Harbor, VA.
Fought on 2 Jun 1864 at Cold Harbor, VA.
Fought on 28 Aug 1864.
Fought on 1 Oct 1864.
Fought on 17 Nov 1864 at Petersburg, VA.

JR