The American Civil War (1861-1865) stands as a pivotal chapter in U.S. history, where government principles and societal dynamics collided in a tumultuous struggle. Deep-rooted differences over state sovereignty and slavery erupted into a brutal conflict, testing the very foundations of the nation. The secession of Southern states challenged the federal government's authority, prompting an emotionally charged battle to preserve the Union. As the war raged on battlefields and the home front, Abraham Lincoln's leadership navigated the nation through its gravest trial. The war's outcome redefined the balance of power between federal and state entities, while the scars left behind underscored the high cost of maintaining a united republic.