In John Freely’s book “he Grand Turk: Sultan Mehmet II – Conqueror of Constantinople, Master of an Empire and Lord of Two Seas” we can read that Vlad The Impaler killed many Christian victims.
Cited
“Vlad justified these massacres on grounds of piety, which rings all the more false since the majority of his victims were civilians, and Christians just like him.”
Source
John Freely, The Grand Turk: Sultan Mehmet II – Conqueror of Constantinople, Master of an Empire and Lord of Two Seas, I.B. Tauris (Bloomsbury Publishing), 1st edition, 2009. ISBN-13: 978-1-59020-248-7; ISBN-13: 978-1-84511-704-7.
Balkan Academia 