Origin
On February 23, 1862, the United States War Department issued General Orders No. 20, creating, “A new military department, to be called the Department of the Gulf.” The new department comprised “all of the coast of the Gulf of Mexico west of Pensacola harbor and so much of the Gulf States as may be occupied by the forces under Major General B.F. Butler.” On March 20, 1862, Benjamin Butler arrived at Ship Island, Mississippi, and issued General Orders No. 1 (Department of the Gulf) assuming his new command.
The Capture of New Orleans
Shortly after Butler assumed command, U.S. naval forces, led by Admiral David G. Farragut, captured the port city of New Orleans on April 29, 1862. As commander of Union troops in the Department of the Gulf, Butler assumed the role of military governor of New Orleans after his soldiers marched into the city on May 1, 1862. During Butler’s tenure, the forces under his command, now known as the Army of the Gulf, functioned primarily as an army of occupation.
Banks Replaces Butler
Butler’s hardline rule over the next five months engendered the enmity of citizens throughout the South and earned him the nickname of “the Beast.” His harsh policies eventually forced President Lincoln to recall the controversial general. On November 9, 1862, Secretary of War Edwin Stanton issued General Order No. 184, replacing Butler with Major General Nathaniel P. Banks in command of the Department of the Gulf.
Union Victories at Fort Bisland, Irish Bend, and Port Hudson
When Banks assumed control of the department, the Army of the Gulf comprised only the 19th Corps. In 1863, the Army of the Gulf took part in three major engagements, the Battle of Fort Bisland (April 12, 1863–April 13, 1863), the Battle of Irish Bend (April 14, 1863), and the Siege of Port Hudson (May 22, 1863—July 9, 1863), all Union victories.
Increase in Size
Beginning in August 1863, the number of troops available to Banks began to swell. The 13th Army Corps moved down the Mississippi River to various parts of the Department of the Gulf. In February 1864, the War Department also dispatched two divisions from the 16th Army Corps to the Department of the Gulf.
Red River Campaign
With over 30,000 soldiers at Banks’ disposal by the spring of 1864, Chief-of-Staff Henry Halleck ordered Banks to launch a campaign against the remaining Confederate forces in Louisiana. Despite Banks’ reservations about the operation (along with the concerns of Ulysses S. Grant and William T. Sherman) the Army of the Gulf, supported by Rear Admiral David Dixon Porter’s U.S. Naval forces, embarked upon the Red River Campaign on March 12, 1864. Two months later, Banks limped back to Louisiana after suffering decisive defeats at the Battle of Mansfield (April 8, 1864), and the Battle of Pleasant Hill (April 9, 1864).
The Red River Campaign was a Federal fiasco, perhaps the biggest of the war. Besides casualty totals that topped 8,700 soldiers, the expedition siphoned men and material away from other operations, perhaps extending the war. The disastrous campaign somewhat sullied Porter’s reputation, but it ruined Banks. Shortly after Banks returned to southern Louisiana the U.S. War Department issued General Orders No. 192, on May 7, 1864. The order placed the Department of the Gulf under the dominion of the newly created Division of West Mississippi, commanded by Major General Edward Canby. Reduced to an administrative role, Banks would never again command troops in the field.
Diffusion and Dissolution
Following the Red River disaster, army officials dispersed many of the Army of the Gulf’s troops. On June 11, 1864, the War Department discontinued the 13th Corps designation and transferred the troops to other commands. In July 1864, officials deployed the 1st and 2nd Divisions of the 19th Corps to Virginia to take part in the Shenandoah Valley Campaign of 1864.
Units remaining in the department saw some further action during the summer of 1864. On August 3, 1864, U.S. Naval vessels put ashore nearly 1,500 troops from the Army of the Gulf near Mobile, Alabama. The soldiers from those units then took part in the siege and capture of Fort Gaines (August 3–8, 1864) and the siege of eventual capture of Fort Morgan (August 9–23).
On November 7, 1864, the War Department discontinued the 16th and 19th Corps. On November 25, 1864, the army transferred the units of the old 19th Corps still in Louisiana to the Reserve Corps, Army of the Gulf. Two divisions of the 16th Corps traveled to Nashville, Tennessee in time to take part in the Franklin-Nashville Campaign.
On February 18, 1865, the army reorganized the 13th and 16th Corps. Under the command of Major General Edward Canby, those troops took part in the siege and capture of Fort Spanish (March 27-April 8, 1865) and Fort Blakely (April 2-9, 1865), which eventually led to the occupation of Mobile, Alabama. Historians often cite the storming of Fort Blakely as the last major infantry action of the Civil War east of the Mississippi River.
The War Department officially discontinued both corps on July 20, 1865.