The figures born on this date span centuries and continents, but the most consequential among them may be the one who, by most reckonings, helped bring an entire system of government to its end. Julius Caesar, born in 100 BC, rose through the Roman Republic's institutions to dominate them utterly — his military campaigns, his crossing of the Rubicon, and his assumption of perpetual dictatorship set in motion the collapse of republican Rome and the eventual rise of imperial rule. The senators who assassinated him in 44 BC feared what he had become, but the civil wars that followed only accelerated the transformation he had begun. His life remains a case study in how concentrated ambition, given sufficient talent and opportunity, can reshape the political order of an entire civilization.