What are James Buchanan's accomplishments as president?

James Buchanan (1791–1868) served as the fifteenth president of the United States. He was in the White House from 1857 to 1861. A recent poll of political scientists ranks him as next-to-last, just ahead of Donald Trump. Most historians agree that he was an inept president. His abysmal ranking is due to his failure to prevent the Civil War (1861–1865).
Buchanan entered the presidency with a weak mandate. He had only won a plurality—not a majority—of votes cast in the 1856 presidential election.
The Supreme Court gave its momentous Dred Scott decision just after his inauguration in 1857. In this case, the Court stated that the federal government had no right to prohibit slavery from the territories. The case supported the South's view, and it was reviled in the North. Buchanan thought slavery was morally wrong, but he tried to mollify the South during his presidency. He did this by supporting the pro-slavery Lecompton constitution for Kansas, trying to purchase Cuba, and enforcing the Fugitive Slave Act.
The election of Abraham Lincoln in 1860 meant that efforts at compromise were doomed. South Carolina seceded from the Union. Other states soon followed. Buchanan vacillated and left the crisis to Lincoln, who became president in March 1861.
https://www.businessinsider.com/greatest-us-presidents-ranked-by-political-scientists-2018-2