Who is Laura Chappell McAllan from Mudbound and what is their importance?

Laura is a thirty-one year old spinster when Henry McAllan comes into her life and changes everything. Henry, a college educated man who works with the Army Corps of Engineers, marries Laura and gives her two daughters and a good life in Memphis. However, after World War II draws to a close, Henry buys a farm in the Mississippi Delta, tearing Laura from the only world she has ever known and dumping her into the rural farm country to make a home in a rustic house that has no electricity or running water.