A handshake was enough to seal an agreement, because trust was the foundation of every commitment. In any case, the true strength of an agreement lies in mutual trust. After all, a contract without trust is just a piece of paper from which a good lawyer will always know how to get out. And for war? We are the most ruthless, bloodthirsty, power-hungry species on this earth. Have a agreement or treaties ever blocked the will of autocratic dictators that we ourselves often bring to power with our vote? Maybe for a while, not till they are defeated or satisfied.