Who was the President of the United States during the Civil War?

Abraham Lincoln was the President of the United States during the Civil War, which lasted from 1861 to 1865. He played a crucial role in leading the nation through this tumultuous period, emphasizing the preservation of the Union and the abolition of slavery. His leadership was characterized by significant events such as the issuance of the Emancipation Proclamation in 1863, which declared that all slaves in Confederate-held territory were to be set free, and his commitment to maintaining the Union ultimately resulted in victory for the North. Lincoln's effectiveness as a wartime leader and his vision for the nation post-war had a lasting impact on the United States' identity and future.

The other individuals listed were not in office during the Civil War, making their relevance to the question clearer. Thomas Jefferson served as the third President prior to Lincoln and was not involved in the Civil War era. Ulysses S. Grant was a Union general during the Civil War and later became the 18th President, but he did not hold the presidency during the conflict itself. Andrew Johnson succeeded Lincoln after his assassination and was in office during the early Reconstruction period, but he was not the president during the actual Civil War years.