Among the personal hobbies which Horace recommends his young friend Lollius conduct at a discreet distance from his potens amicus is the re-enactment of the battle of Actium, which should only be undertaken in the privacy of his father’s estate. Critics have noted that the potential offence in this seemingly affirmative celebration of the ‘miracle of Actium’ lies in the casting of Lollius’ brother as his opponent, thus acknowledging the civil nature of the battle which was at least downplayed, if not elided, in official discourse. They have overlooked, however, the further subversive element in Horace’s reference to ‘whichever of the two (alterutrum)’ Victory crowns. This presents the counterfactual possibility, both in the Epistle and in the naumachia which serves as a parallel mimesis, that Antony might have won the battle of Actium. This instance of ‘sideshadowing’ demands to be set in a number of contexts, such as the use of counterfactuals in historiographical depictions of battles and the phenomenon whereby some public naumachiae had outcomes contrary to that of the historical battle they were re-enacting. In particular, the very possibility of an Antonian victory renders the Augustan principate contingent, in opposition to the providential, teleological inevitability with which it, and especially its foundational battle, were depicted elsewhere in Augustan poetry. Such an interpretation is supported by Lucan’s allusion to this passage in his Dyrrachium episode, the only other non-Lucretian instance of alterutrum in extant Latin poetry.