The document summarizes several key Civil War battles from Fort Sumter in April 1861 to the Battle of Antietam in September 1862. It describes how the Confederate forces attacked Fort Sumter, leading to its surrender after 34 hours, and several southern states subsequently seceding from the Union. Several early battles resulted in high casualties that exceeded all previous American wars. The Union suffered defeats at Bull Run but had victories capturing forts and cities in Tennessee and New Orleans. The bloodiest single-day battle of the war occurred at Antietam in September 1862, with over 26,000 casualties, after which Lee retreated back to Virginia.