Dionysius I of Constantinople

[2] During the Fall of Constantinople in 1453 he was enslaved by the Ottomans, but he was bought and freed some time later in Adrianople by an archon known as Kyritzes (probably Demetrios Apokaukos, one of the two Greek secretaries of Sultan Mehmed II).

[2] At that time the Patriarchal throne was contested by two factions, one led by the lay archons George Galesiotes (the Great Chartophylax) and Manuel Christonymos (the future Patriarch Maximus III of Constantinople), the other composed of the nobles of the former Empire of Trebizond who were forced to move to Constantinople after Trebizond's fall to the Ottomans in 1461.

[4] In 1466 Symeon I was successful in deposing Mark II and obtaining the throne after presenting the Ottoman government with 2000 pieces of gold.

Symeon I's first reign lasted only a short time because his simoniac action outraged Mara Branković, who went to Constantinople to complain to Mehmed II.

The date of appointment of Dionysius as Patriarch is most likely the end of 1466 because on 15 January 1467 he signed an act by which the Holy Synod stripped of any ecclesiastic dignity George Galesiotes and Manuel Christonymos.