XIII Corps ( Union Army ) XIII Corps was a corps of the Union Army during the American Civil War . It was first led by Ulysses S . Grant and later by John A . McClernand and Edward O . C . Ord . It served in the Western Theater of civil war , Trans - Mississippi Theater and along the Gulf of Mexico . Corps History . Creation . The XIII Corps , along with the XIV Corps , were both put into commission on October 24 , 1862 with the passing of General Orders No . 168 . These two corps were the first corps created in the Western Theater . While the XIV Corps constituted all forces under the command of William S . Rosecrans , the XIII Corps likewise constituted all the forces under Ulysses S . Grant . Because of the corps ' immense size and it was virtually synonymous with the Army of the Tennessee , Grant chose to subdivide the corps into the Right , Left and Center wings . In December 1862 it was officially divided inton the XIII Corps , XV Corps , XVI Corps and XVII Corps . Grant remained in command of the Army of the Tennessee and John A . McClernand assumed command of the XIII Corps . Before the official order was passed along to all the wing commanders , William T . Sherman , commander of the Right Wing , embarked on an expedition against Vicksburg . Sherman ' s wing of the XIII Corps fought the Battle of Chickasaw Bayou on December 26 – 29 . Although the official date which the Right Wing was designated the XV Corps was December 22 , most of the reports regarding the battle at Chickasaw Bluffs still refer to the Union forces as part of the XIII Corps . No matter what it was the first time many of the troops had been under fire . Arkansas Post . Adding to the identity crisis the XIII Corps faced in its early years was John A . McClernand ' s expedition against Fort Hindman at Arkansas Post . McClernand was given his XIII Corps and Sherman ' s XV Corps ( now officially using that designation ) . McClernand labeled these forces the Army of the Mississippi and renamed the XIII Corps " I Corps " and the XV Corps " II Corps " . McClernand commanded the Army and placed General George W . Morgan in command of the I Corps ( former XIII Corps ) . The divisions of Andrew J . Smith and Peter J . Osterhaus participated in the battle . Only Stephen Burbridge ' s brigade of Smith ' s division bore any heavy fighting . Vicksburg . With the impending campaign against Vicksburg , Grant took personal command of the operation . McClernand returned to corps command and the Army of the Mississippi was merged back into the Army of the Tennessee and the XIII Corps took on its official title . As the Vicksburg campaign opened the XIII Corps was composed of the 9th , 10th , 11th , 12th , 13th and 14th Divisions commanded respectively by Osterhaus , A . J . Smith , Alvin P . Hovey , Leonard F . Ross and Eugene A . Carr . Ross ' division was stationed in Arkansas during the entire campaign and did not participate in any engagements with the rest of the corps . In July , this division ( now led by Frederick Salomon ) fought at the Battle of Helena as part of the District of Eastern Arkansas under Benjamin M . Prentiss . The Battle of Port Gibson was fought by the XIII Corps , with the aid of a portion of the XVII Corps . McClernand did not bring the full force of the corps to bear at the Battle of Champion Hill but Hovey ' s division led the attack on the Confederate right . Immediately following the victory at Champion ' s Hill the Battle of Big Black River Bridge was again fought exclusively by the XIII Corps , Carr ' s division bearing the brunt of the fight . When Grant initiated siege operations the XIII Corps took up a position on the Union left . During the assaults on Vicksburg the XIII Corps lost nearly 1 , 500 soldiers . McClernand had been a long time thorn in Grant ' s side and on June 19 , Grant found an opportunity to remove him from command . His replacement was Edward O . C . Ord , a friend of Grant ' s who had just recovered from a wound sustained in 1862 . Ord led the corps throughout the rest of the siege . After Vicksburg fell , William T . Sherman led an expedition back to Jackson , MS to clear the city of Confederates which had gathered there . Sherman took with him the XIII Corps and attached to it the division under Jacob G . Lauman from the XVI Corps . General Carr , who temporarily left the army due to sickness , had been replaced in division command by William P . Benton . Texas and Louisiana . After the fall of Jackson the corps returned to Vicksburg and then transferred to the Department of the Gulf . The District of Eastern Arkansas had been detached from the Corps ; AJ Smith had been reassigned to command a post in Tennessee ; Osterhaus had been reassigned to command a division in the XV Corps ; Hovey took leave of the army due to the death of his wife ; two of the divisions in the field were consolidated under the command of Cadwallader C . Washburn ; and General Herron ' s division was attached . General Banks used the XIII Corps to conduct his coastal campaign against Texas during the fall of 1863 , capturing Brownsville . By February 1864 corps headquarters were in Texas and General McClernand had returned to command . Red River . The 1st and 2nd Divisions remained in Texas but Nathaniel P . Banks took with him the 3rd and 4th Divisions during the Red River Campaign . During the first part of the campaign the corps was commanded by Thomas E . G . Ransom , the 3rd Division by General Robert A . Cameron and the 4th Division by Colonel William J . Landram . The corps fought at the Battle of Mansfield . Ransom was wounded at Mansfield and was succeeded in command of the corps by General Cameron . A few weeks later Michael K . Lawler of the 1st Division in Texas became the official corps commander . General McClernand however assumed direct command of the two divisions fighting in Louisiana under Banks . McClernand was relieved of command due to ill health and Lawler himself personally commanded this detachment . Shortly after William P . Benton was assigned to the corps command but Lawler remained in command of the detachment in Louisiana . Lawler led the XIII Corps Detachment at the Battle of Mansura . Mobile . The corps was discontinued on June 11 , 1864 . On February 18 , 1865 it was reorganized under the command of Gordon Granger with three divisions commanded respectively by James C . Veatch , Christopher C . Andrews and William P . Benton . This new form of the XIII Corps fought in the Battle of Fort Blakely which led to the fall of the city of Mobile , Alabama . The corps was discontinued for the final time July 20 , 1865 . The men of the XIII Corps were never designated an official corps badge and therefore never wore any form of a corps badge during the war .