Numerous as are the historical notices in former years regarding the destruction of armies by pestilence, correspondingly few are the detailed reports on the spread of pestilence among the non-belligerent population. The best-known example from antiquity is the _Plague of Athens_ (430–425 B.C.), described by Thucydides. The plague began in the second year of the Peloponnesian War, a few days after the invasion of the Peloponnesians. That it is famous is due to the classical description of it by Thucydides, himself a sufferer from the disease. The Plague of Athens broke out in the Piraeus, a fact which has led to the inference that it was borne thither by mariners from Egypt. At the time of the invasion of the Peloponnesians, thousands of country people fled to the city of Athens, which on the advice of Pericles opened its gates to them; thus more than 400,000 people were crowded together within its walls. The first outbreak of the plague lasted two years, then there was an intermission of a year and a half, whereupon it commenced anew. The second outbreak, according to Diodorus, carried away 4,400 hoplites, 300 cavalrymen, a large (but uncertain) number of other soldiers, and 10,000 women and slaves. The plague also penetrated to other places, sparing, however, the Peloponnesus. The nature of the sickness described by Thucydides cannot be positively determined; it has been referred to as bubonic plague (Sprengel), as small-pox (Krause-Daremberg, Kobert), as typhus fever (Häser, Kanngiesser), as typhoid fever (Seitz), and even as anthrax. All we know for certain is that it was some highly infectious disease, recovery from which rendered a person immune. Krauss and Hecker believe that it was a special disease (‘antique plague’), which no longer occurs.[3] The _Plague of the Antonines_, also called the ‘Plague of Galen’, which ravaged Italy in A.D. 166–8, has also been brought into connexion with warlike events. Avidius Cassius, who preceded Verus in command of the army, had been sent to Syria for the purpose of suppressing a rebellion, and there, after the capture of Seleucia, the plague broke out. It was borne by the troops back to Rome, where, after the triumphal procession of 166, it spread far and wide, so that it was necessary to load its victims on wagons and carry them off for burial. The plague spread from Italy to Gaul, to the very banks of the Rhine, and a large part of the province was literally depopulated—decayed and deserted villages were found everywhere. Häser inclines to the view that it was an epidemic of small-pox, while Laveran, Hecker, Krause, and Littré believe that it was neither small-pox nor typhus fever, but ‘antique plague’.[4]