The Treaty of Versailles was created after WWI, and one of its objectives was to try to avoid another war as destructive as the one that had just passed. Great Britain and France, among others, believed that much of the war was a consequence of German aggression and militarism. Therefore, they attempted to curtail these. They forced Germany into a situation in which its armed forces were severely restricted. Germany also lost about 13% of its territory and was forced to pay substantial fees.
All of these served as fuel to motivate nationalist sentiments, such as the ones the Nazis had long defended. Britain and France did not understand Hitler because they did not grasp what his goals were, nor how far he would go to achieve them. Hitler was convinced of the injustice of the treaty, and he became obsessed with dismantling it. He "weaponised" the document, and advocated extreme measures in order to regain the position that Germany had enjoyed. He was also willing to act in extreme ways in order to achieve this.
