Martinus (son of Heraclius)

One such partisan, Valentinus, led troops to Chalcedon, across the Bosporus strait from the imperial capital, Constantinople, to force Martina to install Constans II, the son of Constantine III, as co-emperor.

[2] Prior to taking the throne in 610, Heraclius had been married to Fabia Eudokia, with whom he had had a daughter, Eudoxia Epiphania, and a son, Constantine III.

[8][10] A partially preserved papyrus letter known as SB VI 8986, and another papyrus document, CPR XXIII 35, shows that Martinus was definitely promoted to caesar at some point between 639 and 640, although the exact dating is debated: the German papyrologist who restored SB VI 8986, Fritz Mitthof [de], and the Byzantine historian Nikolaos Gonis argue for a date range between October 639 and September 640,[11][12] whereas Byzantine scholar Constantin Zuckerman argues for a range between 4 January 639 and 8 November 639.

[12] According to the 7th-century historian John of Nikiu, Martinus and his brother David were involved in the banishment of Ecumenical Patriarch Pyrrhus of Constantinople (r. 638–641) to the Exarchate of Africa.

However, the two princes were too young at the time to have taken an active role in any banishment and the account by John of Nikiu is so contradictory that no safe conclusions can be drawn from it.

[15] Despite these overtures, Valentinus entered Constantinople shortly thereafter, deposed Heraclonas and Martina, and then elevated Constans to sole emperor.