L. Munatius Plancus to Cicero, written in camp on the march from the Is\‘ere down toward Forum Voconii on 18 May 43 BC — Perseus dateline Scr. in castris ex itinere ab Isara Forum Voconi xv K. Iun. a. 711 (43). This is the dispatch in which Plancus explains, while it is still happening, why he has decided to march south to join Lepidus rather than wait, as caution would have counselled, for D. Brutus to cross the Is\‘ere with his army and come up to him.

The strategic problem is acute. Antony has reached Forum Iulii; Lepidus, with seven legions, is at Forum Voconii twenty-four miles inland; Lepidus’s army is notoriously of doubtful loyalty (the “inconstancy and unreliability” Plancus and Cicero both fear); Lepidus himself is now writing pleading letters, doubled up by even more urgent ones from his legate Juventius Laterensis. If Plancus stays back on the safer line and Lepidus is overwhelmed — or, worse, peeled away by his own troops — the resulting collapse will be laid to Plancus’s account either as obstinacy or as cowardice. Better to take the risk, push down to join Lepidus, and try to hold the army together by physical presence. The fourth section gives the operational details: he has broken camp on the 18th of May, but left the bridge over the Is\‘ere standing, with two forts and strong garrisons at its heads, so that when D. Brutus comes up he can cross at once.

The military-administrative register is at its strongest here, with Plancus weighing alternatives in the unmistakable voice of a serving commander explaining a field decision to his political patron. The image of the hidden wound is the sentence Shackleton Bailey marked as Plancus’s most arresting — “I cannot help shuddering, if some wound is festering beneath the skin which can do its damage before it can be either known or treated.” And the contempt for Antony’s quartermaster Ventidius Bassus (“Ventidi mulionis castra” — “the muleteer Ventidius’s camp,” from the well-worn jibe that he had once driven mule-trains in his youth) is the one piece of openly partisan colour. Within ten days of writing this letter, Plancus will have joined Lepidus, and the army about whose loyalty he and Laterensis were so anxious will have gone over to Antony en masse.