Herodian relates that he had an existing animosity towards Gordian, on account of an unspecified lawsuit. Gordian, on his acclamation as co-emperor with his father Gordian I (governor of the neighbouring province of Africa), ordered the replacement of Capelianus. The latter refused to go quietly, however, and took an army to Carthage, where his numerically superior and well-trained forces (Numidia, in contrast to Africa, was well-garrisoned against Berber raids) easily defeated those of Gordian. He then allowed his soldiers free rein to pillage Africa, hoping to maintain their favour in the event of an opportunity to make a bid for emperor himself. Such an opportunity presumably never arose, as we hear no more about him.
- Herodian, History of the Roman Empire 7.9