I believe that Fischer was trying to identify the major groups of English speakers that migrated to the New World and had the most influence on our culture. The Cavaliers or Royalists apparently accomplished their greatest numbers of emigrants during the period noted, I think, because of the Cromwell and Roundhead turmoil. They were, I think, migrating to the crown colony which was begun by the Jamestown settlers. The statement I made about the revolution and the Borderers was because the Borderers(Scotch Irish) came to the New World with a great amount of enmity toward the Crown and they were inherently rather rebellious. No doubt though that many of the intellectual leaders of the Revolution were of the Cavalier class and the first few presidents were of that class. I need to study up on that part of history.