The French and UK governments barely defeated Germany. The economic restrictions on Germany were clearly insufficient, and as Germany started rearming nothing was done even though Germany was clearly violating the conditions imposed on it.

Meanwhile, after WW2, when Germany was actually crushed with millions more dead and their economy was truly collapsed, peace finally was achieved.

The lesson here is to actually defeat Russia, thoroughly, without holding back.

Same with Gaza. It is absurd that a single member or supporter of Hamas is allowed to live.