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(Friday, April 12, 1861, 4:30 a.m. local time; during the Battle of Fort Sumter, part of the American Civil War) — The American Civil War, a civil war fought between northern states loyal to the Union and southern states that had seceded to preserve the enslavement of black people, began early today when secessionist forces attacked Fort Sumter in the harbor of Charleston, South Carolina.

Confederates bombarded the fort from artillery batteries surrounding the harbor. Although the Union garrison returned fire, they were significantly outgunned and, after 34 hours, Major Robert Anderson of the U.S. Army agreed to evacuate.

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There were no deaths on either side as a direct result of this engagement, although a gun explosion during the surrender ceremonies on Apr. 14, 1861, caused the death of two U.S. Army soldiers.

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The Union and the Confederacy quickly raised volunteer and conscription armies that fought mostly in the South for the next four years. Intense combat would leave between 620,000 and 750,000 soldiers dead, along with an undetermined number of civilians.

The American Civil War remains the deadliest military conflict in American history, and accounted for more American military deaths than all other wars combined until the Vietnam War.