Odaenathus assembled the Palmyrene army and Syrian peasants, then marched north to meet the Persian emperor, who was returning to Persia. The Palmyrene monarch fell upon the retreating Persian army between Samosata and Zeugma, west of the Euphrates, in late summer 260. He defeated the Persians, expelling Shapur I from the province of Syria. In early 261, Fulvius Macrianus headed to Europe accompanied by Macrianus Minor, leaving Quietus and Balista in Emesa. Odaenathus' whereabouts during this episode are not clear; he could have distributed the army in garrisons along the frontier or might have brought it back to his capital. The Palmyrene monarch seems to have waited until the situation clarified, declaring loyalty to neither Fulvius Macrianus nor Gallienus. In the spring of 261, Fulvius Macrianus arrived in the Balkans but was defeated and killed along with Macrianus Minor; Odaenathus, when it became clear that Gallienus would eventually win, sided with the Emperor and marched on Emesa, where Quietus and Balista were staying. The Emesans killed Quietus as Odaenathus approached the city, while Balista was captured and executed by the King in autumn 261. Ruler of the East The elimination of the usurpers left Odaenathus as the most powerful leader in the Roman East. He was granted many titles by the Emperor but those honors are debated among scholars: Dux Romanorum (commander of the Romans) was probably given to Odaenathus to recognize his position as the commander in chief of the forces in the east against the Persians; it was inherited by Odaenathus' son and successor Vaballathus. Corrector totius orientis (righter of the entire East): it is generally accepted by modern scholars that he bore this title. A corrector had overall command of Roman armies and authority over provincial governors in his designated region. There are no known attestations of the title during Odaenathus' lifetime. Evidence for the King bearing the title consists of two inscriptions in Palmyrene: one posthumous dedication describing him as MTQNNʿ of the East (derived from the Semitic root TQN, meaning to set in order); and the other describing his heir Vaballathus with the same title, albeit using the word PNRTTʿ instead of MTQNNʿ. However, the sort of authority accorded by this position is widely debated. The problem arises from the word MTQNNʿ; its exact meaning is unclear. The word is translated into Latin as corrector, but "restitutor" is another possible translation; the latter title was