I'll start the list off by nominating Bismarck as the most successful political leader of the last few centuries. He was a master of internal politics who bent a series of governments to his will; he was a visionary who pursued a singular goal over a period of decades; he used military force to gain his objectives in a series of wars, but he prepared the way for those wars by setting the diplomatic preconditions for success; he understood and manipulated his international opponents; he limited the objectives of war to what was desirable and achieveable and consciously abandoned force when his overall strategic goal was achieved; he used the military but allowed the professionals to get on with the conduct of the war - until they threatened to upset the proper relationship between policy and war, when he brought them up short; and finally, he created an international system that preserved the peace and Germany's place in the sun for more than a generation.

Yes, he was not a nice man. Yes, his system broke down when lesser men - including one certified congenital idiot - tried to operate it. Still, WWI was neither inevitable nor directly the fault of Bismarck. All in all, I can't think of a more successful practitioner. And, he was a cavalryman.