The first modern Republic occurred in Holland led by the Dewitt brothers who were eventually torn apart by a mob of political opponents in favor of a return to royal rule. Locke, Hume, John Stewart Mill and even Aristotle seemed to favor democracy in some form; they did not excoriate it.
The Roman Republic was created in 509 BC. It actualized some of the shape of the Republic Plato wrote about. Rome had two consoles and The Republic had two philosopher-kings. Plato wrote The Republic circa 375 BC. Socrates wanted a restoration of oligharchy and Rome may have provided and abstract template to synthesize with a Spartan social structure. Rome's Republic was more like a democracy than Plato might have liked.
American founders of democracy were in revolt against authoritarianism and social class supremacy; those were perennial challenges for the polis in needing to get rid of royalty.
