They just weren't Catholic, they were Orthodox, a point that will become relevant shortly. We're going to skip the Second Crusade because it bores me and move on to the Third Crusade because it's the famous one. Broadly speaking, the Third Crusade was a European response to the emergence of a new Islamic power, neither Turkish nor Abbasid. The Egyptian, although he was really a Kurd, Sultan Amalik al-Nasr Salih al-Din Yusuf, better known to the West as Saladin. Saladin, having consolidated his power in Egypt, sought to expand by taking Damascus and eventually Jerusalem, which he did successfully because he was an amazing general. And then the loss of Jerusalem caused Pope Gregory VIII to call for a Third Crusade. Three of the most important kings in Europe answered the call.