 Pope Gregory VIII called for a Third Crusade against the Muslims in early 1189 . Frederick Barbarossa of the Holy Roman Empire , Philip Augustus of France , and Richard the Lionheart of England formed an alliance to reconquer Jerusalem . Meanwhile , the Crusaders and the Ayyubids fought near Acre that year and were joined by the reinforcements from Europe . From 1189 to 1191 , Acre was besieged by the Crusaders , and despite initial Muslim successes , it fell to Richard 's forces . A massacre of 2 @,@ 700 Muslim inhabitants ensued , and the Crusaders then planned to take Ascalon in the south . 
