The Battle of Arkansas Post, also known as the Battle of Fort Hindman, was fought from January 9 to 11, 1863, along the Arkansas River at Arkansas Post, Arkansas, as part of the Vicksburg campaign of the American Civil War. Confederate forces constructed Fort Hindman near Arkansas Post in late 1862. Also in late 1862, Major General John A. McClernand of the Union army (as the United States Army was known during the war) was authorized to recruit troops in the Midwest for an expedition down the Mississippi River against Vicksburg, Mississippi. Union Major General Ulysses S. Grant began an overland campaign against Vicksburg along the Mississippi Central Railroad in November. He and Union General-in-Chief Henry Halleck did not trust McClernand, and through machinations placed the start of the riverine movement against Vicksburg under the command of Major General William T. Sherman before McClernand could arrive. Sherman's movement was defeated at the Battle of Chickasaw Bayou in late December, and Confederate cavalry raids forced Grant to abandon his overland campaign.
McClernand arrived at Memphis, Tennessee, in late December and found that Sherman had left without him. McClernand moved downriver, joined Sherman's force, and took command in early January 1863, calling it the Army of the Mississippi. Both Sherman and McClernand had independently come to the conclusion that Arkansas Post should be attacked: Confederate forces raiding from Fort Hindman had recently captured a Union supply vessel, and Sherman may have been hoping for a victory to restore his reputation after Chickasaw Bayou. McClernand's troops and a Union Navy fleet commanded by Acting Rear Admiral David Dixon Porter moved upriver towards the Arkansas River. The expedition began unloading troops downriver from the fort late on January 9. The next day, some of Porter's warships bombarded the fort, while McClernand's troops maneuvered into position. At 1:00 pm on January 11, Porter's warships began another bombardment of the fort, and McClernand's troops attacked the Confederate positions, which consisted of the fort and a line of rifle pits that extended west to a bayou.
McClernand's attack was repulsed, but white flags of surrender began to appear over parts of the Confederate line in uncertain circumstances. Confusion ensued, and Union troops moved up close to the Confederate line and swamped parts of it. The Confederate commander, Brigadier General Thomas J. Churchill, agreed to surrender. When Grant learned of the operation against Arkansas Post, he disapproved and ordered McClernand back to the Mississippi River, although Grant was later convinced of the wisdom of the operation. Grant relieved McClernand on January 30 and took command of the campaign against Vicksburg. In April and May, Grant's army crossed the Mississippi River downriver from Vicksburg and won a series of battles. The Confederate forces withdrew into the Vicksburg defenses in mid-May. The Siege of Vicksburg ended with a Confederate surrender on July 4, 1863; this was a key contribution to the eventual Union victory.
Initial Union plans and operations
Early in the American Civil War, the Union (as the United States was known during the war) military leadership developed the Anaconda Plan, a strategy to defeat the Confederate States of America by controlling its coastline and the Mississippi River. Much of the Mississippi Valley fell under Union control in early 1862 after the capture of New Orleans, Louisiana, and several land victories. The strategically important city of Vicksburg, Mississippi, was still in Confederate hands, and it served as a strong defensive position that commanded the river and prevented the Union from separating the eastern and western halves of the Confederacy. Union Navy vessels were sent upriver from New Orleans in May to try to take the city, a move that was unsuccessful. In late June, a joint army–navy expedition returned to make another campaign against Vicksburg. The Union Navy leadership decided that the city could not be taken without more infantry, who were not forthcoming. An attempt to construct Williams's Canal across a meander of the river in June and July, bypassing Vicksburg, failed.
In early November 1862, Union Major General Ulysses S. Grant began concentrating troops at Grand Junction and La Grange, Tennessee, in preparation for a campaign into the state of Mississippi along the Mississippi Central Railroad, with Vicksburg as its goal. After a delay in Tennessee to await reinforcements, Grant's troops set out in late November, and his part of the movement contained about 31,000 men, with another 17,000 in a supporting force under the command of Major General William T. Sherman. Grant at this time commanded the Department of the Tennessee, which consisted of Cairo, Illinois; Forts Henry and Donelson in Tennessee; the area west of the Tennessee River in Tennessee and Kentucky; and northern Mississippi. All of the troops in the department were part of the XIII Corps, which had a complex organizational structure.
In September, Major General John A. McClernand had discussed with President Abraham Lincoln a campaign down the Mississippi River to take control of the river, as McClernand (a former politician turned military officer) believed that Confederate control of the river was dampening support for the war in the Old Northwest. Despite some hesitancy from high-ranking Union military and political figures about McClernand's suitability for an independent command, an arrangement was reached whereby McClernand was permitted to recruit soldiers in the Midwest and then take this force downriver to operate against Vicksburg. McClernand received secret orders from Secretary of War Edwin Stanton regarding the expedition on October 21. These orders, which had originated from Lincoln but had been influenced by Halleck, gave McClernand a theoretically independent command operating in the military department commanded by Grant, and McClernand believed his command was independent. Instead, the ambiguous wording of the order gave General-in-Chief Henry Halleck the ability to redirect the troops McClernand raised for other purposes; it also stated that McClernand's operation could proceed "when a sufficient force not required by the operations of General Grant's command shall be raised". In effect, both Halleck and Grant had the power to override McClernand's campaign.
Halleck used this language in the official orders to undercut McClernand, whom he distrusted. Halleck transferred McClernand's newly recruited troops to Memphis, Tennessee, or Helena, Arkansas, as they entered service. On December 5, Halleck suggested to Grant a naval operation down the Mississippi River against Vicksburg, using a portion of Grant's force. At that time, Grant was growing concerned about the length of his supply line in Mississippi, as well as the condition of the roads ahead. Halleck had informed him that the downriver movement had the support of the President, and Grant assumed that McClernand, who Grant had a low opinion of, would command the movement. Grant decided to take control of McClernand's recruits, and placed them under the command of Sherman, who was to lead them on a riverine expedition down the Mississippi River to Vicksburg. Sherman had command of over 30,000 men, drawn from Memphis and Helena, and one division that Sherman took from Grant's main column. Presidential orders issued on December 18 divided the XIII Corps into four separate corps: a smaller XIII Corps, the XV Corps, the XVI Corps, and the XVII Corps. McClernand was given command of the new XIII Corps, but this division of the old XIII Corps did not immediately take effect as active operations by the corps were ongoing. McClernand was to command "that part of the army which was to operate down the Mississippi". Grant, in turn, knowing that Sherman was expected to begin the expedition in a matter of days, sent McClernand a letter (intentionally eschewing the faster telegraph service) authorizing him to take command of the force moving downriver. This message was not received because of Confederate cavalry raids in western Tennessee.