In Elizabeth Kostova's fascinating Dracula novel, The Historian (NY: Back Bay, 2006), there is the following exchange between the undead Prince Vlad and one of the mortal charactres:
. . .‘I have nearly fulfilled my ambition of printing fourteen hundred and fifty three of them, but slowly, so that I have time to distribute them as I work. Does that number mean anything to you?’
‘Yes,’ I said after a moment. ‘It is the year of the fall of Constantinople.’
‘I thought you would see it,’ he said with his bitter smile. ‘It is the worst date in history.’ (pp. 605-6)
I thought this sentiment a highly plausible one for him to express on two counts. First, Raymond McNally and Radu Florescu describe Dracula's father's visit to Constantinople, saying, 'Vlad's first glimpse of the glamour and glitter of the dying thousand-year-old civilization of Byzantium made an indelible impression' (Dracula, Prince of Many Faces [Boston: Back Bay, 1989], p. 38). It's hard to imagine the son did not share his father's feelings.
Second, Dracula spent his entire life in a vain effort to stem the flood of Muslim Turks into the Orthodox lands of the Balkans. Had Constantinople held, his kingdom too might have stood strong and independent, and he himself might have lived into old age.
The illustration above is by Benjamin Constant, 'The Entry of Mahomet II into Constantinople' (1876).