This decisive battle at the Horns of Hattin took place on July 4, 1187. It is generally considered to be the single largest defeat inflicted upon the christian armies by the Islamic armies led by Saladin, or more properly Salah al-Din Yusuf bin Ayub.
"I saw the limbs of the fallen cast naked on the field of battle, lacerated and disjointed with heads cracked open, throats slit, spines broken, necks shattered, members disbembered, noses mutilated, breasts flayed, spirits flowen. Their ready ghosts crushed like stones among stones."

Imad ad-Din

Saladin went on to retake Jerusalem from the Christians in October of the same year.