I think the single sentence that shows it is a personal letter is "that all I can say is that I am well" as the rest of the letter is details about his military campaign so could be part of a more formal memo if it were not for this opening sentence so that seems to be how to identify it as such.
What was Virginia Woolf famous for? She was best known for her novels, especially Mrs. Dalloway (1925) and To the Lighthouse (1927). She also wrote pioneering essays on artistic theory, literary history, women's writing, and the politics of power.
