Our present predicament of omnipresent uncertainty, sudden twists of fate and the sense that a serious menace looms somewhere beyond our reach make it all the more understandable what seafaring people and coastal communities fear most about piracy – both in the present and the past. Like a foreign disease that washes upon the beach, piracy has been such a threatening aspect of life at sea because it appears out of nowhere, unchecked by rules on violence or raiding. A ship appears on the horizon, seemingly friendly at first, but then flags change and a chase on the vast expanses of the high seas begins. In the nineteenth century, piracy on the Mediterranean Sea was, in fact, even considered by some to be a type of plague that had to be fought with unprecedented security measures. As such, the historical repression of piracy touches upon enduringly relevant topics of security, violence, law and the dynamics of international inclusion and exclusion. My dissertation on the nineteenth-century fight against Mediterranean piracy, which I recently defended at Utrecht University, uncovers the dynamics of security during a pivotal moment in history and shows how piracy repression helped remake the Mediterranean into a space of European imperial expansion.