The answer is: The Byzantine emperor.
I hope this helps.
Have a nice day.
^-^
Byzantium/Constantinople was conquered in 1451, but the empire continued to decline starting around the 18th or 19th centuries. It officially died in WWI. As for how long it was a major threat to Europe, the empire's prime was the 16th century, under Suleiman the Magnificent.
Hey there!
The answer is a Chancellor
Hope it helped!
