Complex sentence: He now participated, for nearly two years, in the work of the Second Vatican Council which had started its deliberations back in October 1962, although he would later come to be seen as unsympathetic to some of The Council's more "liberal" outcomes.
Split into simpler sentences: He now participated, for nearly two years, in the work of the Second Vatican Council which had started its deliberations back in October 1962. He would later come to be seen as unsympathetic to some of The Council's more "liberal" outcomes.