Situated at the mouth of Charleston harbor in South Carolina, Fort Sumter is the place where it began. America's most tragic conflict ignited at Fort Sumter in April of 1861, when a building of tensions and disagreements over social, economic and political events exploded into civil war. At the heart of these events was the underlying issue of slavery in the southern states. Fueled by decades of disagreement and confrontation, based on states rights versus federal authority, and political fears, South Carolina and other southern states seceded from the Union and formed the Confederate States of America. On April 10, 1861, General Beauregard, in command of Confederate forces at Charleston, demanded the surrender of the Union garrison of Fort Sumter in Charleston Harbor. The United States commander Anderson refused. On April 12, Confederate cannons opened fire on the fort, which was unprepared to effectively counter. On April 13, Fort Sumter surrendered and was evacuated on the 14th. The bombardment of Fort Sumter was the opening engagement of the American Civil War.