Like many of James Michener's tomes, Chesapeake is historical fiction. As such, it is part of a popular American genre in which the historical background serves to lend verisimilitude to the episodic organization of the narrative and veracity to the themes of the novel: the interconnection of modern America with Early America, and the interconnection of the human world with the natural world. It is also part of American thought that historical contexts assist people in the learning process as they realize that much can be gleaned from this awareness of historical facts.
In addition, the character of Rosalin Jenney who marries into ealthy landed gentry of the Steeds, plays the role of the feminist in the novel, baring her back when women considered "wayward" are publicly whipped. Her doing so causes the practice to end. Another issue of American thought is the demise of the American Indian. With Roe v. Wade in 1973, and the feminist movement beginning, Jenney's act is relevant to contemporary times.
Another issue broached in Michener's novel is the dilemma of the Native-Americans. The Nantichokes, Native-Americans indigenous to the Chesapeake Bay area eventually disappear for the area bringing to light the plight of the Indians.
The environmental issues, of course, are relevant to Michener's time of authorship. In the 1970s the National Environmental Policy Act was signed into law, and responsibility for clear air and water shifted to the federal government. His subplot of the Paxmores, a Quaker family that has immigrated to the area because of religious persecution provides a relevancy to current times as one of the descendants, Pusey Paxmore, serves a prison sentence for his part in the Watergate Scandal. (ronically, Richard Nixon himself was a Quaker.) The Paxmores, also, are earlier in the novel very involved in the Underground Railroad. As Michener ties in many other historical events, "cameo appearances are made by homas Jefferson, John Smith, Henry Clay, Daniel Webster, and George Washington, to name a few. With these famous events and names, Michener may hope to pique his readers' interest in history, the greatest teacher of all.