The 1899 Porto plague outbreak was an epidemic of bubonic plague centered in the city of Porto, in the north of Portugal. The arrival of plague in the Portuguese city of Porto signalled the first outbreak of the third plague pandemic in Europe, attracting international attention, due to fears of a return of the Black Death in the continent. It also pitched local and national authorities as well as medical experts in heated arguments about the nature of the disease and the way to contain it, namely, the controversial decision to surround the city by a military-enforced cordon sanitaire for four months, imposed by the government of Prime Minister José Luciano de Castro.