France wanted revenge on Germany after World War I primarily because of the harsh terms of the Treaty of Versailles, which was signed in 1919 to formally end the war. The treaty imposed heavy penalties and reparations on Germany, including massive territorial losses, military disarmament, and a large financial debt.
France, which had suffered significant damage and loss of life during the war, saw the Treaty of Versailles as a way to weaken Germany and prevent it from posing a threat in the future. However, the treaty also left Germany in a state of economic and political instability, which contributed to the rise of Adolf Hitler and the Nazi Party in the 1930s.
When Germany invaded and occupied France during World War II, many French people saw it as an opportunity to seek revenge for the humiliation and suffering they had experienced during World War I. This sentiment was particularly strong among members of the French resistance, who fought against the German occupation and collaborated with the Allies to defeat Germany.
Overall, France's desire for revenge on Germany after World War I was driven by a combination of factors, including a desire to weaken Germany as a potential aggressor, the economic and political consequences of the Treaty of Versailles, and the emotional and psychological trauma of the war itself.