Paul von Hindenburg
Paul von Hindenburg was a German general and politician. He became a national hero in the opening weeks of World War I by winning a decisive victory over the Russians in the Battle of Tannenberg. Along with Erich Ludendorff, he was transferred to the Western Front in 1916 to replace Falkenheyn and commanded the German army there almost until the end of the war.
In the early 1930s he became president of the Weimar Republic. He was quite elderly at the time and may not have been aware that by cooperating with Adolf Hitler, he was leading his country into another ruinous world war.
Hindenburg and Ludendorff were overrated as generals. The groundwork for Tannenberg was all put in place by Prittwitz before they even arrived, yet they took credit. The Spring offensive in 1918 was an utter catastrophe. There was poor strategic planning and the focus of the attack was changed several times. They wasted manpower occupying huge swathes of Russia that they didn't need, then squandered the last of the reserves blundering around aimlessly in France.
Hindenburg should never have been regarded as a war hero. His Nazi-friendly presidency led to the worst disaster in German history.