The English Civil Wars did sharply divide society: the National Army Museum says the war divided friends, families, and local communities, and HISTORY notes that Royalist forces controlled much of northern and western England while Parliamentarians dominated the south and east at the outbreak. (nam.ac.uk) But the split was not neatly binary; a scholarly chapter on the war says most people tried to stay neutral, and the ruling class was split into three groups — royalists, parliamentarians, and neutrals — while the National Army Museum adds that there was no such thing as a “typical” Royalist or Parliamentarian. (blackwellpublishing.com) So the claim is fair as a shorthand for deep polarization, but “split the population in two” overstates how cleanly and uniformly people aligned. (blackwellpublishing.com) Sources: National Army Museum, “British Civil Wars”; HISTORY.com, “English Civil Wars”; Blackwell Publishing sample chapter, “The English Civil War” (from *What Was the English Revolution?*). (nam.ac.uk)