American Civil War: The first Union infantry assault of the Siege of Port Hudson occurs.

The American Civil War was a civil war in the United States between the Union and the Confederacy, which was formed in 1861 by states that had seceded from the Union. The central conflict leading to war was a dispute over whether slavery should be permitted to expand into the western territories, leading to more slave states, or be prohibited from doing so, which many believed would place slavery on a course of ultimate extinction.

The siege of Port Hudson was the final engagement in the Union campaign to recapture the Mississippi River in the American Civil War. While Union General Ulysses Grant was besieging Vicksburg upriver, General Nathaniel Banks was ordered to capture the lower Mississippi Confederate stronghold of Port Hudson, Louisiana, to go to Grant's aid. When his assault failed, Banks settled into a 48-day siege, the longest in US military history up to that point. A second attack also failed, and it was only after the fall of Vicksburg that the Confederate commander, General Franklin Gardner, surrendered the port. The Union gained control of the river and navigation from the Gulf of Mexico through the Deep South and to the river's upper reaches.