Bury them drenched in pigs blood with their asses facing Mecca.Islams fighters are and always have been far more barbaric than any other armies, with the exception of the SS Nazis during WWII. Even some US troops committed some atrocities during WWII. War brings out the extreme animalistic nature in some individuals and groups. For example, if I was fighting against Islamists, I would upon killing them, remove their heads and ensure the heads couldn't be reunited with the bodies. It impacts them religiously. Know not only your enemies' strengths, but also their weaknesses.