Helmuth von Moltke the Younger
Helmuth von Moltke the Younger (1848-1916) rose to Field Marshal and Chief of the German General Staff at the start of World War I, but mismanaged the Schlieffen Plan for the attack. This resulted in disaster at the First Battle of the Marne.
He had been an adjutant to his uncle, Helmuth von Moltke the Elder, and done well in the Franco-Prussian War. Becoming a friend of Crown Prince Wilhelm, he remained close when Wilhelm became Kaiser Wilhelm II.