The lesson is that not to take punishment to an extreme,or that harsh punishment is not the ideal way to solve a conflict,as it might backfire.
After WWI,Germany was punished harshly for starting the war by supporting Austria-Hungary. The punishment involved was to pay a great war dept of 33 billions, disarming(no air craft allowed,reduced army to 100000 men etc.) . It has caused much problem to the nation such as hyperinflation, unemployment etc.
This finally led to the up-rise of totalitarianism, in which the nation become aggressive in order to get national glory, and many jews were killed in blame of hindering Germany's development the or even leading to her defeat. It finally post a world threat and caused the outburst of WWII. If the punishment was not as harsh, totalitarianism could be avoided as well as WWII. Thus the lesson is that not to push the matter too hard and be more lenient
