The Siege of Port Hudson was a significant military operation during the American Civil War, aimed at securing complete control of the Mississippi River for the Union. The first Union infantry assault occurred when Major General Nathaniel P. Banks ordered an offensive against the fortified position held by Confederate General Franklin Gardner in Port Hudson, Louisiana. Banks's strategy was driven by the need to consolidate Union control of the Mississippi, following victories at Vicksburg and New Orleans. On May 27, 1863, approximately 14,000 Union soldiers launched their attack against the well-entrenched Confederate forces. The Union troops managed to push forward initially, but were met with a strong defensive fire from Confederates who were deeply dug into their positions, utilizing rifles and artillery to repel the advancing soldiers. This resulted in severe casualties for the Union forces, as they were unable to fully capitalize on their initial advantages in the early stage of the assault.

The battle showcased the difficulty of frontal assaults against fortified positions and the deadly consequences of such tactics. The Union assault concluded with significant losses, prompting a reassessment of their assault strategies. Following the failed assault, the siege continued for several weeks. Union forces laid siege to Port Hudson and used artillery bombardments alongside continuous ground assaults, until the surrender of the Confederate garrison on July 9, 1863. The eventual Union victory at Port Hudson was pivotal, as it marked the last major Confederate holdout along the Mississippi River, ensuring a significant strategic advantage for the Union in the Western Theater of the war.