What was meant by the phrase ruled by "blood and iron?"?

Question

Otto Von Bismarck

Answer 1

Ruled by killing people and use of violence.....the blood refers to killing and iron refers to swords and other weapons used to kill and punish people.

Answer 2

This phrase refers to a country that had been ruled by a dictatoric tyrant who had no mercy on his people and who threw them into jail and killed many of them.