*) as the host and mediator of the Congress of Berlin.  
As ambassador to Russia, he met and befriended Prince Gorchakov, who would later become one of his greatest adversaries, when the Prince would denounce him as having denied Russia's victory by the modification of the Treaty of San Stefano.  The League of Three Emperors thus fell apart during that same month-long meeting he led to decide upon the Eastern Question (*) as the host and mediator of the Congress of Berlin.  Seven years later, he organized another conference in Berlin to decide the fate of African colonization, which precipitated the Scramble for Africa.  FTP, name this German Chancellor to Emperor Wilhelm I, who famously proclaimed the great questions of the day will be decided by iron and blood. 
As ambassador to Russia, he met and befriended Prince Gorchakov, who would later become one of his greatest adversaries, when the Prince would denounce him as having denied Russia's victory by the modification of the Treaty of San Stefano.  
Otto von {Bismarck}