This, after he had vowed to fight to the bitter end.

CNN: Liberia: Sweet land of liberty now bitter, broken

Another contributor was the expansion of international peacekeeping forces, which really do keep the peace not always, but far more often than when adversaries are left to fight to the bitter end.

WSJ: Steven Pinker: Why Violence Is Vanishing

And it's been a very bitter fight, so it strikes me as being pretty hard to put that together at the end of the day.

NPR: Obama Re-Writes History, Clinches Party Nomination