According Byzantine historian
Michael Doukas there was another Ottoman prince, who was
Bayazid's (1360 – 1403 ) son, that he baptized Orthodox Christian, probably around 1417.
Doukas. HISTORY, chapter XX , 4.TRANSLATION by Harry J Magoulias - (1975, Wayne State University Press), PAGE 112.
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Bayazid's eldest son, who was included among the hostages handed over by Sulayman to Emperor Manuel, was released with his sister Fatma and reared in Prusa.
The other son 120* acquired a passion for Greek learning. He accompanied John, the emperor's son, to school and there as a student he was introduced to intellectual matters.
So absorbed was he by the love of learning when he attended school with John that he came to Emperor Manuel and requested to be baptized according to Christian law.
Daily he professed to the emperor that he was a Christian and not a believer in Muhammad's doctrines.
The emperor did not wish to listen because it might cause scandal.
Then when the dreaded disease continued to consume and destroy bodies, neither respecting nor sparing any age, it attacked Bayazid's adolescent son.
The stricken youth sent the following message to Emperor John, "0 Emperor of the Romans, you who are both master and father to me, my end is near.
Against my wishes I must leave everything behind and depart for the Heavenly Tribunal.
I confess that I am a Christian and I accuse you of not granting me the darnest of faith and the seal of the Spirit. 121*
Know, therefore, that as I must die unbaptized, I shall bring accusations against you before the Judgment Seat of the impartial God."
Yielding finally to his plea, the emperor sent for him and as his godfather sponsored his baptism.
He died the next day. The emperor buried him with great honor in a marble sarcophagus near the church and within the gate of the Studite Monastery of the Prodromos...''122*
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Notes by Harry J Magoulias, at page 288 :
120*. Barker, MP, pp. 253-54n88, has not understood Doukas in this instance. Doukas says that Bayazid's first son and daughter Fatma, who had been sent to Manuel as hostages, were both later released. A second son, however, seems to have stayed on at the imperial court and became a Christian before he died, evidently of the plague. His name was probably Yusuf and when he was baptized he took the Christian name of Demetrios. See Moravcsik, 2:118, 141, 144.
121.* "The seal of the Spirit," in the Greek Orthodox church, means the sacrament of Chrismation or Confirmation which immediately follows baptism.
122*. The famous Monastery of Studion, named for St. John the Baptist and Forerunner (Prodromos), was founded in the 5th century (A.D. 463) by the Roman patrician Studius in southwest Constantinople.
According to Doukas the death of the converted Turkish prince took place in 1417. Van Milligen, BC, p. 36.
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