George Sphrantzes was the Emperor Constantine XI's personal secretary and a friend. According to his own account of the conquest of Constantinople, his daughter Thamar (named Therma in the series) was 12 years old when the city fell and was taken into captivity by the Turks, dying in the Sultan's harem in September 1455 of an infectious disease. Therefore, the series inaccurately portrays her as having escaped to the island of Chios, which was then controlled by Genoa. There is also no evidence that Thamar and Giovanni Giustiniani Longo, the leader of the Genoese mercenaries, were in a romantic relationship.
Contemporary accounts do report, on the other hand, that the mortally-wounded Giustiniani was carried off to a Genoese galley which then headed for Chios. Giustiniani died either en route or shortly after arriving on the island and was buried in the Church of San Domenico (later the Church of Santa Maria del Castello, which eventually was converted into a mosque following the Turkish conquest of the island in 1566). The tomb is now lost.
Contemporary accounts do report, on the other hand, that the mortally-wounded Giustiniani was carried off to a Genoese galley which then headed for Chios. Giustiniani died either en route or shortly after arriving on the island and was buried in the Church of San Domenico (later the Church of Santa Maria del Castello, which eventually was converted into a mosque following the Turkish conquest of the island in 1566). The tomb is now lost.