Martin I, pope (649 - 655), succeeded Theodore I in June or July 649. He had previously acted as papal apocrisiarius or legate at Constantinople, and was held in high repute for learning and virtue. Almost his first official act was to summon a synod (the first Lateran) for dealing with the Monothelite heresy. It met in the Lateran church, was attended by one hundred and five bishops (chiefly from Italy, Sicily, and Sardinia, a few being from Africa and other quarters), held five sessions or secretarii from October 5 to October 31, 649, and in twenty canons condemned the Monothelite heresy, its authors, and the writings by which it had been promulgated. In this condemnation were included, not only the Ecthesis or exposition of faith of the patriarch Sergius for which the emperor Heraclius had stood sponsor, but also the typus of Paul , the successor of Sergius, which had the support of the reigning emperor (Constans II). Martin was very energetic in publishing the decrees of his Lateran synod in an encyclical, and Constans replied by enjoining his exarch or governor in Italy to seize the pope, should he persist in this line of conduct, and send him prisoner to Constantinople.

These orders were found impossible to carry out for a considerable space of time, but at last Martin was arrested in the Basilica di San Giovanni in Laterno on June 15, 653, hurried out of Rome, and conveyed first to Naxos and subsequently to Constantinople by September 17, 654. After suffering an exhausting imprisonment and many public indignities, he was ultimately banished to Cherson in the Crimea, where he arrived on March 26, 655, and died on September 1 of that year.

Original text from the 9th edition (1880s) of an unnamed encyclopedia