Interesting, i thought that the church was a power center that was complementary if not secondary to the secular powers of western Europe. However you seem to be saying, that the formal legitimacy granted by the Eastern Roman Empire was more important to maintain some very fragile equilibrium between the church vs the state, and that this equilibrium was then lost with the church schism.

I find it somewhat hard understand, how the church managed to mobilise europe into a crusade, it is possible that the various competing establishments weren't very enthusiastic about the project, to begin with.