Complex sentence: The Pennsylvania Abolition Society, of which Hopper became an active and leading member, was frequently called upon to protect the rights of African Americans, and in time Hopper became known to everyone in Philadelphia as a friend and adviser to blacks in all emergencies.
Split into simpler sentences: The Pennsylvania Abolition Society, of which Hopper became an active and leading member, was frequently called upon to protect the rights of African Americans. In time, Hopper became known in Philadelphia as a friend and adviser to blacks in all emergencies.