The president of the United States during the Civil War was Abraham Lincoln. He served as the 16th president from 1861 until his assassination in 1865. Lincoln led the country through the Civil War, working to preserve the Union and playing a key role in the abolition of slavery. His presidency began just as the conflict started, with the war officially beginning in April 1861 after Confederate forces attacked Fort Sumter. Lincoln issued the Emancipation Proclamation in 1863 and was re-elected in 1864. He managed the war effort as commander-in-chief and sought to reunify the nation through reconciliation before his death in 1865