What was one notable achievement of Abraham Lincoln?

One notable achievement of Abraham Lincoln was saving (or preserving) the Union during a time of severe national crisis. Lincoln served as President during the American Civil War, which was primarily fought over issues such as states' rights and slavery. His leadership was crucial in maintaining the integrity of the United States amidst the secession of Southern states and the ensuing conflict.

Lincoln's commitment to preserving the Union was evident in his various policies and the issuance of documents such as the Emancipation Proclamation, which aimed not only to abolish slavery in Confederate-held territories but also to weaken the Confederate war effort. By prioritizing the unity of the nation, he ensured that the United States could emerge from the war as one country, laying the groundwork for future civil rights advancements and the eventual abolition of slavery.

The other options, while significant, do not fully encompass the central objective of Lincoln’s presidency during the Civil War. The expansion of U.S. territory did happen under other administrations, and even though Lincoln played a role in initiating steps toward freeing slaves, it was not his singular achievement. Lastly, the Great Depression occurred long after Lincoln’s death, making it unrelated to his legacy. Thus, Lincoln's most notable achievement is often regarded as his role in preserving the Union