James Buchanan, elected president of the United States in 1856, was, at the time, the most experienced leader elected president since James Madison:

• He had run a law firm
• In his twenties, he served in the Pennsylvania state legislature
• He served in the U.S. House of Representatives
• He was minister to Russia for Andrew Jackson
• He served in the U.S. Senate
• Franklin Pierce sent him to Britain as the American minister there
• He served as James Polk's Secretary of State
• By two different presidents, he was offered, but turned down, a seat on the Supreme Court
• He was candidate for president himself in 1844, 1848 and 1852 finally winning in 1856

And...drum roll please...James Buchanan is largely regarded by historians as our worst president ever. 

Worse than Hoover, who presided on the doorstep of The Great Depression?  Yep.  Worse than Harrison, who was president about a month?  Yep.  Worse than Garfied, who wasn't president much longer than that?  Yep.

Worse than Tyler, Polk and Taylor?  Yep, yep and yep.  Fillmore and Pierce? Yep, yep.  Worse than Nixon...the only president to resign in shame after being impeached?  Oh, by far, yes.

The main problem was that Buchanan was a man with dueling loyalties.  He was from a union state (Pennsylvania), but was prosouthern.  When you live in two worlds with two different loyalties, it's impossible to lead people in one direction. He had cabinet members who were actively conspiring against the United States.

He displayed an "arrogant, wrongheaded, uncompromising use of power," writes Jean Baker in her 2004 biography of him.  According to Baker, he was "too ideological for the pragmatic necessities of a large diverse democratic republic."

He leant a deaf ear to the majority of Americans.  He could not read the American landscape.

Much later, he bragged to anyone who would listen that the Civil War did not start on his watch.  He was right about that.  It started about six weeks after he was done.  Abraham Lincoln was left to clean up his mess.

Although, in hindsight, the Civil War is viewed as inevitable, back then it was not.  And Buchanan is "credited" with laying the groundwork by his pigheadedness, split loyalties, at times confused frozen inaction and at other times arrogant assumption that others would go along with his policies.

They did not.