The Peace Prize seems somewhat hit or miss. I'm sure we all remember when it was given to Barack Obama for his lifelong work of not being George W Bush. And of course it was given to Henry Effin' Kissinger.
Maybe this speaks to the difficulty of peace in general. One asshole warmonger can destroy thousands of lives on a whim, but ending or preventing war takes long, steady efforts by large numbers of people. It's not very amenable to an individual prize.