regiment, on his letter of April 23, 1863, as brigades going below Hernando to Cold Water.
During March of 1863 the regiments was assigned to the 3rd Brigade of the 16th Corps of the Department of the Tennessee.
On May 10, 1863 the regiment embarked on board transports for Vicksburg, Mississippi and it reached Young’s point on May 11, 1863. On May 24, 1863 six companies, ( may have been five companies, official records differ), of the 87th regiment were ordered back to Warrenton to perform guard duty and assist with unloading of boats on the Mississippi.
The remaining companies, commanded by LT. Colonel Crebs, as part of the 2nd Brigade (63rd, 87th, 120th, and 131st Illinois regiments, under the command of Colonel McCowan) joined in the Vicksburg campaign closing up the gap on the extreme left of the line of investment. There they remained for 6 hours under a steady fire of shot and shell from the enemy’s works at Vicksburg. During the six hours of engagement regimental sharpshooters engaged confederate batteries. Private Henry McKnight (F Company) was shot in the cheek. On June 24,1863 the Warrenton detachment rejoined the regiment and was assigned to the 2nd Brigade, 12TH division, 13 Corps of the Department of the Tennessee, where they were sent back into the trenches surrounding Vicksburg..
After the fall of Vicksburg, on the night of July 4.1863, the regiment, under the command of Lieutenant Colonel Crebs, along with the 47th Indiana, 56th Ohio, 24th Iowa, 28 Iowa, 2nd Ohio Battery and one section of 1st Missouri Battery, moved out on a five day march to Jackson Mississippi. During this march the regiment suffered from fatiguing and extreme heat. On the morning of the 10th one company from each of the assigned regiments advanced as a line of skirmishers, encountering Confederate pickets. . After a few well directed volleys from the skirmishers, the Confederate forces retreated behind their fortifications at Jackson. The union forces entrenched and continued fire upon the Confederate position. After seven days of the siege the Confederate forces evacuated Jackson Mississippi. During this engagement the 87th reported 3 wounded. The regiment returned to Vicksburg Mississippi on July 25, 1863 and embarked for Natchez. There it made an excursion back in the county to Kingston, capturing a vast pile of Confederate cotton.
In August 1863 the regiment was assigned to the 2nd Brigade (Colonel James Slack Commanding 87th Illinois, 47th Indiana, 24th Iowa, 28 Iowa, 56 Ohio, 1st Missouri Light Artillery Battery A, and 2nd Ohio Battery), 3rd Division (General A. L. Lee Commanding), 13 corps of the Army and Department of the Gulf (Major General Wasburn command in the absence of Major General Ord). On August 10, 1863 the regiment, along with the 47TH Indiana Regiment, embarked on transports and proceeded to Natchez Mississippi, arriving on August 12, 1863. They went into camp below the city. According to the report of the Adjutant General of the State of Illinois the 87TH regiment was the first western troops making the decent of the Mississippi River. On August 13, the regiment marched toward the Big Black River and camped near Kingston. It then returned to Natchez and embarked on transports for New Orleans and debarked at Carrollton Louisiana. The regiment, along with 13th Corps, was reviewed in formation by Major General Banks, on August 27, 1863.. The regiment remained in camp until the September 13, 1863, during which time General Grant reviewed the regiment, together with the whole army stationed there.
From September 1863 until February 1865, the regiment was mounted and served with the Cavalry primary with the 1st and 3rd Cavalry brigades of the Army and Department of the Gulf, under the command of General A.S. Lee. On September 13, 1863 the regiment crossed the river to Algiers and moved by rail westward to Brashear City on Berwick Bay where it remained until September 28, 1863.
Colonel John E. Whiting resigned his commission on October 8, 1863 with LT. Colonel John M. Crebs receiving his promotion to full colonel and command of the 87TH regiment on the same date.
The regiment crossed Berwick Bay and moved to Opelousas, arrives there on October 23, 1863. During September and October 1863 the regiment was engaged in the movements along the Atchafalaya River and Bayou de Paul. On November 8, 1863 the regiment marched to Vermillion Bayou, returning to New Iberia on November 16, 1863. “Order of Battle” dated November 30, 1863 has the 87th, 16th Indiana, and 1st Louisiana as First Brigade commanded by Colonel Thomas L. Lucas; under the overall command of General A. L. Lee (commanding cavalry). The regiment remained at New Iberia until January 2, 1864, when they fell back to Franklin Louisiana where they went into winter quarters until March 13, 1864.
During January 1864, the regiment conducted a recruitment drive in White County and surrounding county area. Ninety- eight men were recruited after January 19, 1863. Of the last forty men recruited, for the 87TH regiment, only three mustered out with the regiment. Twenty-eight were transferred to other regiments (mostly to the 18TH Illinois infantry) and three others died of disease.