It is increasingly well understood that concepts of 'humanitarian intervention' and the 'responsibility to protect' enjoy a long and rich history. Nevertheless, it is surprising how plainly the arguments offered by states seeking to justify intervention in Libya in 2011 echo those used by theologians, jurists, and philosophers to justify intervention in the sixteenth, seventeenth, and eighteenth centuries. Those advocating intervention in Libya drew not just on the language of 'human rights,' that emerged relatively recently, but on a wider and much older range of idioms and ideas to make their case. In this article, I identify three key arguments that were employed by states in support of the intervention and I demonstrate their parallels with three principal arguments that have been advanced to justify intervention in response to tyranny since the sixteenth century. The three arguments are: the need to protect 'innocents'; the need to hold 'tyrants' to account; and the need to defend the will of a sovereign people. After exploring each argument, I conclude by noting that the claim often heard today, that intervention is under certain circumstances a responsibility rather than merely a right, also has deep roots in early modern thought.