Over thousands of years it's also been common for defeated peoples to nurse grudges and find ways to stick it to their conqueror. That's why wars tend not to be one-off things; like potato chips, one just isn't enough. The entire point of the modern shift towards trying to use "mutual concessions and compromise" is to break these cycles. The only way you get lasting peace is if you turn your enemies into friends.
UN aid chief says no warring parties observed Yemen truce (Reuters)
from the article: The fixation of power