M. Brutus to Cicero, written from his camp circa 23 June 43 BC — Perseus dateline Scr. in castris circ. ix K. Quint., a. 711 (43), “circa the ninth day before the Kalends of Quintilis,” i.e. nine days before 1 July. Brutus is by now in Macedonia or northern Greece, consolidating the eastern forces and treating his command as a wartime headquarters.

The letter is a short note of recommendation. The consul C. Vibius Pansa, mortally wounded at Forum Gallorum, has died of his wounds (23 April 43), and his vacant augural college seat is being filled by co-option. Brutus asks Cicero to nominate L. Calpurnius Bibulus — his stepson, the son of his wife Porcia by her first husband M. Calpurnius Bibulus the consul of 59 — for the place. The plea is delicate: Bibulus is family on Brutus’s side twice over (his stepson and the son of Cato’s son-in-law), but the appeal is made on personal ties rather than politics. Domitius (probably Cn. Domitius Ahenobarbus, Brutus’s young commander on the fleet) and Apuleius (M. Apuleius, quaestor in Asia who has handed Brutus the treasury he campaigns on) are mentioned in passing as needing no special letter; both will reappear in later correspondence.