Martinus or Marinus was caesar of the Byzantine Empire from 638–September/October 641. Martinus was the son of Emperor Heraclius and Empress Martina. Under Heraclius, Martinus was elevated to caesar in 638. Heraclius left the Byzantine Empire to two of Martinus' brothers, Constantine III and Heraklonas; Constantine soon died of tuberculosis, though some of his partisans alleged that he was poisined by Martina. One such partisan, Valentinus, led troops to Chalcedon to force Martina to make Constans II, the son of Constantine, co-emperor. Valentinus seizedConstantinople regardless in September/October 641, and deposed Martina, Heraklonas, and Martinus, and cut off Martinus nose and emasculated him, before exiling him to Rhodes.
History
Martinus was born to Byzantine Emperor Heraclius and Empress Martina at an unknown date. Martinus was declared a nobilissimus under Heraclius, while the elder brother Tiberius was made caesar on 4 July 638. According to the Byzantine historian Nicephorus Gregoras, Martinus was also made caesar on the same day, however the later historian and Emperor ConstantineVII mentions only Tiberius. A partially preserved papyrus letter known as SB VI 8986, and 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,, and the Byzantine historian Nicolas Gonis argue for a date range between October 639 and September 640, whereas Byzantine scholar Constantin Zuckerman argues for a range between 4 January 639 and 8 November 639. According to John of Nikiu, Martinus and his brother David were involved in the banishment of Pyrrhus of Constantinople to the Exarchate of Africa. This could be seen as a reaction to Pyrrhos bypassing David and Martinus after the death of Heraclius. 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.
Reign of Constantine III and Heraklonas
When Heraclius died on 11 February 641, he declared in his will that Constantine III and Heraklonas would co-rule the empire under the regency of Martina. The Byzantine Senate accepted Constantine III and Heraklonas as co-emperors, but rejected Martina as regent. On 20/24 April or 26 May 641, Constantine died of an advanced case of tuberculosis, although some supporters of Constantine alleged that Martina had him poisoned, leaving Heraklonas as the sole ruler under the regency of Martina. In August 641, Valentinus, a general who had been loyal to Constantine before his death, led his troops to Chalcedon to force Martina to elevate Constans II to co-emperor. A mob rose up in the city, demanding that Patriarch Pyrrhus must crown Constans II as emperor, and then abdicate, to be replaced by his steward Paul II, who would come to replace him as Patriarch under Constans II. Martina, now in a truly desperate situation, offered the military further donatives, recalled an influential patron of Valentinus, Philagrius, from his exile in Africa, and offered Valentinus the title of Count of the Excubitors.
Valentius' revolt and Martinus' death
In late September/October, Martina elevated Constans to co-emperor, but also raised Heraklonas brother Tiberius to co-emperors alongside them. Despite these offers, Valentinus entered the city shortly thereafter, deposed Heraklonas and Martina, and then elevated Constans to emperor. Heraklonas, Martina, Tiberius, and Martinus are said by John of Nikiu to have been "escorted forth with insolence", where following, Valentinus had Martinus nose cut off, emasculated him and then banished him to Rhodes, where he stayed until his death. Another son, Theodosius, suffered no punishment as he was deaf-mute, and thus was not in a position to threaten the throne.
