Three Guineas.

Although Three Guineas is a work of non-fiction, it was initially conceived as a "novel–essay" which would tie up the loose ends left in her earlier work, A Room of One's Own. The book was to alternate between fictive narrative chapters and non-fiction essay chapters, demonstrating Woolf's views on war and women in both types of writing at once. This unfinished manuscript was published in 1977 as The Pargiters. When Woolf realized the idea of a "novel–essay" wasn't working, she separated the two parts. The non-fiction portion became Three Guineas. The fiction portion became Woolf's most popular novel during her lifetime, The Years, which charts social change from 1880 to the time of publication through the lives of the Pargiter family. It was so popular, in fact, that pocket-sized editions of the novel were published for soldiers as leisure reading during World War II.