Alright, so Einstein came up with SR to make Maxwell's EM consistent with dynamics, correct? But SR was only for non-inertial reference frames and ignored gravity, so it was replaced with GR to make SR consistent with gravity. So why have I read (from many sources) that Einstein spent his later years (from 1925 onward) trying to find a way to reconcile GR and EM? Was SR compatible with EM, but somehow GR wasn't? Did some of the changes made between SR and GR conflict with Maxwell's EM?