In WWI, Hitler wasn’t promoted past a private because he lacked leadership skills!
During World War I, Hitler served as a runner on the Western Front. He did experience major combat and was decorated for bravery, receiving the first and second class Iron Crosses.
He interacted with senior officers often, but he was never promoted because they thought he lacked leadership skills. After the war and the collapse, Hitler became embittered and his political ideals began to take root. We all know what happened next.