Heraclius Constantine, or
Constantine III, was the eldest son of
Heraclius. He was also the older half-brother of
Heraclonas, who was the son of Heraclius' second wife Martina. For political reasons Heraclius considered Martina to be mother of them both. Constantine became emperor when Heraclius died in
641, and during his reign the
Arabs conquered
Egypt. He died of
tuberculosis after only four months, leaving Heraclonas sole emperor; it was rumoured, however, that Martina had him poisoned, which led to instability during Heraclonas' reign.