This article examines and contextualizes a health wish formula found at the opening of eight Roman official letters inscribed in Greek, one of Caesar and seven of Octavian. In each letter the sender mentions that he is well ‘with the army’ (μετὰ τοῦ στρατεύματος), hence the term ‘military’ health wish. The health wish was borrowed from Latin letters into Roman letters written in Greek by means of phraseological imitation. The formulation employs appropriate Koine Greek. It was optional during the Republic for the wish to be used in letters either from or to a Roman holding imperium and commanding an army. Because Caesar and Octavian were in such positions, their use of the wish is conventional. The use of this health wish demonstrates that epistolographers working for Caesar and Octavian not only drafted letters that met the conventions of Hellenistic chanceries but also were proficient enough in the medium to incorporate Roman elements with effectiveness. Attestations of the military health wish declined during the Imperial period. The requirement that the sender or the recipient hold imperium would have restricted usage during the Republic but even more so under the Empire through administrative changes to the command of armies and the increasing centrality of the princeps.