- Marcian was a distinguished military officer who had been an aide to the powerful general, Aspar, when he was appointed by the dying Theodosius II to succeed him.
- As part of the arrangement, Marcian, although an old man, married Pulcheria, the virgin sister of Theodosius II.
- Marcian ended the payment of money to the Huns, preferring the sword instead. It is probably this policy that caused Attila to attack the weak Western Roman Empire.
- One of the most important events of Marcian's reign was the Fourth Ecumenical Council held at the city of Chalcedon. There Monophysitism was discussed and declared a heresy.
- Marcian died in 457 without leaving any heirs. He was succeeded by Leo I.