In American history? Not even close.

James Buchanan was so god awful as a person and a president, that his actions and inaction directly lead to the American Civil War and the rise of an armed Confederacy.

He is one of the 4 US presidents so bad that they only served one term, and he was despised by both sides of the isle for his absolute disaster of a presidency. The United States actively regressed under his 4 year tenure.