In 1862, the conflict intensified as key engagements influenced both military strategy and national policy. The bloodiest single-day battle at Antietam halted General Lee’s advances into Union territory, forcing the Confederacy into a defensive posture. Though tactically inconclusive, this battle provided President Lincoln with the moral and political leverage to issue the Emancipation Proclamation, linking military success to far-reaching ethical reforms. Other engagements that year, such as the battles at Shiloh and in the Eastern and Western theaters, further underscored the evolving nature of warfare and marked the transition from early, uncoordinated battles to more strategically comprehensive campaigns.