In early 1864, the Union launched an expedition into Confederate Gen. E. Kirby Smith’s Trans-Mississippi Department, headquartered in Shreveport, Louisiana. Maj. Gen. Nathaniel P. Banks and Rear Adm. David D. Porter jointly commanded the combined force. Porter’s fleet and Brig. Gen. A.J. Smith's Sixteenth and Seventeenth Corps from the Army of the Tennessee set out on March 12, 1864 up the Red River, the most direct route to Shreveport. The major impediment to the Union expedition was the formidable Fort DeRussy, an earthen fortification with a partly iron-plated battery designed to resist the fire of Union ironclads that might come up river. Union Brig. Gen. A.J. Smith’s infantry set out on the morning of the 13th to determine if any enemy was in their path. This force dispersed an enemy brigade, after which Smith set his men in motion up the Fort DeRussy Road. Early the next morning, the 14th, they continued the march. Upon arriving at the fort, the enemy garrison of 350 men opened fire. Smith decided to use Brig. Gen. Joseph A. Mower’s division to take the fort and set about positioning it for the attack. Around 6:30 pm, Smith ordered a charge on the fort and about twenty minutes later, Mower’s men scaled the parapet, forcing the garrison to surrender. Fort DeRussy, which some had said was impregnable, had fallen and the Red River to Alexandria was open.