The 1919 Treaty of Versailles took lots of land away from Germany and awarded it to countries that had fought against Germany in the war. German land was returned or given to France, Poland, and Britain. It is estimated that because of the Treaty of Versailles, Germany lost approximately thirteen percent of its territory.
Under the same treaty, Germany was ordered to pay huge reparations to the Allied countries, amounting to about 132 billion marks. That's the equivalent of about $269 billion today. These reparations were economically devastating to Germany for many years to come.
The 1919 treaty also placed strict limitations on Germany's military. Its army was restricted to just 100,000 men, for example. Germany was also not allowed to have an air force.
However, perhaps worst of all, from a German perspective, was the War Guilt clause. Germany was made to sign this clause to acknowledge that Germany alone was responsible for the war and all of the consequent death and destruction.
The German people considered the terms of the 1919 Treaty of Versailles—and thus, by extension, the armistice between Germany and the Allied countries—to be not only economically devastating but also deeply humiliating. When Hitler and the Nazi Party rose to power in the 1930s, they did so in large part by taking advantage of these feelings of anger, resentment, and humiliation.
Hitler and the Nazi Party promised the German people that they would take back the land they had lost under the Treaty of Versailles. He also promised them that under the rule of the Nazi Party, Germany would rebuild its military strength. Hitler's narrative that the German people were a racially superior race also of course played very well after the humiliation of 1919.