Of all the Roman campaigns against the Parthians, that under the command of the co-emperor Lucius Verus probably presents the greatest difficulties. The essayist Lucian, who had before him not only the bad but also the good histories of the war, has scattered through his essays numerous references to events of the campaign, almost all from writers now lost. The correspondence of Fronto, tutor of the Roman emperors, contains several passages of value, especially in the Principia historiae and in letters from Lucius at the front. Some of this material was not available for the standard edition of Naber, but as a result of further work by Hauler on the palimpsest the Loeb edition by Haines is much more complete. If the campaign of Verus can be worked out more fully than has been done here, it will probably be through further study of the place names and routes involved and by comparison with the usual form of Roman campaign against Parthia, which since the death of Caesar had become fairly well standardized.
Possibly when our knowledge of Parthia in the time of Trajan is much further advanced, we shall be able to untangle the confused account of Malalas and make use of such facts as are present. Now only a small part of the work can be utilized safely.
Concerning other sources not heretofore mentioned, such as Appian, Herodian, those of the Livy tradition, Florus, Orosius, and Rufus Festus, as well as the biographers Suetonius and the "Scriptores," the
