Who is Margaret Winthrop from The Winthrop Woman and what is their importance?

Margaret is John Winthrop's third wife and stepmother to Jack and Harry. A devoted wife and mother, Margaret is described as extremely pious. Margaret and John have seven children, losing one on the voyage to New England and others later, due to ill health. She is seen as a positive force in John's life, and Bess is angry when John remarries very quickly after Margaret's death.