But Gallus' resumption of subsidies did not have the desired effect of sustaining peace on the Danube. Hard on the heels of military catastrophe, the Roman army was crippled by the outbreak of a devastating smallpox pandemic, the so-called Plague of Cyprian (251 - c. 270). The effects of the Cyprianic pandemic are described by Zosimus as even worse than the earlier Antonine outbreak, which probably killed 15-30% of the empire's inhabitants. The Roman army would have suffered heavy casualties as a result of its close concentration of personnel and frequent movements between provinces, thus probably losing about a third of its strength. Taking advantage of Roman military disarray, the transdanubian barbarians launched repeated massive invasions of imperial territory. The exact number, dates and events of these invasions are uncertain due to the confused and fragmentary nature of the sources. It is possible that there were invasions every year and that parts of the Danubian provinces were occupied by marauding bands of barbarians year-round, during the period 251-270. From Zosimus, the following major events may be discerned: