From The Oxford English Dictionary:
blood and iron, n.
. . . .
[A]fter German Blut und Eisen (1862 with allusion to the style of foreign policy advocated by Otto von Bismark, reflecting the phrase Eisen und Blut used by Bismarck in a speech made to the Budget Committee of the Prussian Chamber of Deputies on 20 September of that year; 1785 or earlier in more general use in the sense ‘domination through warfare’).
. . . .
In foreign policy (originally and chiefly that of Otto von Bismarck (1815-98)): the use of military force rather than diplomacy; the advocacy of such an approach.
. . . .
1864 tr. Der Wanderer (Vienna) in Times 22 June 14/4 The man of blood and iron (the Prussian Minister for Foreign Affairs) will not listen to reason.
Link to the rest at The Oxford English Dictionary
Bismarck was an imperialist, a monarchist, and needed public support for his militaristic program. That’s why, even as a conservative, he brought in social security. In order to weld something like 350 states into one under the moral leadership of Prussia and the Junkers class, he needed rhetoric above all else.
Bismark was a serious badass.
Wunderbar! Although ‘realpolitik diplomacy’ is the more… diplomatic way to describe Bismarck’s style.