The greatest thing that Germany lost after World War I was its dignity as it was totally humiliated with the Treaty of Versailles whose 440 Articles demobilised and reduced the military forces of Germany, reduced its lands by 14%, and left 12.5% of the German people living outside German borders. With this treaty, Germany also was stripped of its colonial empire in East Africa. Article 27 stripped Germany of much boundary land, which was distributed to Belgium, Luxemburg, Switzerland, Austria, Czech-Slovokia, Poland, and, of course, France who claimed coal mines in the Saar Basin as reparation for the mines destroyed in France. In addition, Germany was forbidden to build any fortification on the Rhine. Territories ceded in the Treaty of Frankfurt in 1871 were returned to France, as well.
In short, Germany was made to accept full blame for World War I, being required to pay reparations for all the damages done to the allied countries with the War Guilt Clause. This penalty left Germany globally humiliated and bankrupt. After Germany's global humiliation, the once proud Germans were ready to accept such a leader as Adolph Hitler, who promised to make their country powerful again and regain its boundaries.