Research to date on the late antique circus factions and partisans has focused on their land-based activities. The present study, by contrast, considers fourth- to seventh-century sources which demonstrate that members of the maritime community became involved in factional activity and that circus partisans engaged in combat, piracy, and criminal acts at sea. I argue that mariners were important to the factions, as they provided strong-arm support and facilitated Empire-wide trading networks that enabled quick and effective communication between faction members over vast distances. Political and faction leaders were able to exploit these communication networks for their own purposes, such as in the seventh century when Heraclius amassed Green faction supporters, sailors, ships, and other provisions on his voyage to reclaim Constantinople. I furthermore suggest that the support provided to church leaders by the maritime community merits closer investigation because it has all the hallmarks of factional advocacy. Mariners connected people and institutions, carrying the ideologies and protests of the factions, ecclesiastical groups, and imperial patrons with them when they sailed to and from port. The findings of this article, moreover, affirm that the contribution of mariners to the Empire-wide success of such groups should not be underestimated.