Otto von Bismark - the Iron Chancellor
As Minister-President of Prussia from 1862–90, Bismarck oversaw the unification of Germany. When the second German Empire was formed in 1871, he served as its first Chancellor, gaining the nickname "Iron Chancellor".
As Chancellor, Bismarck held an important role in German government and greatly influenced German politics during his time of service. Though probably best known for the quote
"The great questions of the day will not be settled by means of speeches and majority decisions but by iron and blood.”
Bismarck was actually very careful in creating treaties with other nations to ensure stable borders and a peaceful Europe. When the young Wilhelm II became emperor in 1888 and forced Bismarck to resign two years later, Bismarck warned him about being rash in foreign politics and correctly predicted that the Germany empire would crash again if Wilhelm II continued his rash behavior:
"Jena came twenty years after the death of Frederick the Great; the crash will come twenty years after my departure if things go on like this".
He was right, almost to the month, Wilhelm II's rash decisions caused the start of World War I which they decisively lost in October 1918 - 20 years and 2 months after the death of the Iron Chancellor.