Martinus (died c. 641) was caesar of the Byzantine Empire from some point between 638 and 640, to 641. He was the fifth son of Emperor Heraclius and his second wife (and niece) Empress Martina. Heraclius elevated Martinus to caesar, a junior imperial title that placed Martinus on the line of succession. Heraclius died on 11 February 641, leaving the throne jointly to Martinus's half-brother Constantine III and his elder full brother Heraclonas. Constantine III soon died of tuberculosis, though some of his partisans alleged that Martina poisoned him. One such partisan, Valentinus, led troops to Chalcedon, across the Bosporus Strait from the capital, Constantinople, to force Martina to install Constans, Constantine III's son, as co-emperor. Valentinus seized Constantinople, forced Constans II's enthronement in September or October 641, and deposed Martina, Heraclonas, and Martinus. Martinus was mutilated, which killed him. (Full article...)