American Civil War: Union Army troops occupy Baton Rouge, Louisiana.

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.

During the American Civil War, the United States Army, the land force that fought to preserve the collective Union of the states, was often referred to as the Union army, the federal army, or the northern army. It proved essential to the restoration and preservation of the United States as a working, viable republic.

Baton Rouge is the capital city of the U.S. state of Louisiana. It had a population of 227,470 at the 2020 United States census, making it Louisiana's second-most populous city. It is the seat of Louisiana's most populous parish, East Baton Rouge Parish, and the center of Louisiana's second-largest metropolitan area, Greater Baton Rouge, which had 870,569 residents in 2020.