I'm writing this post because there really should be a Wikipedia page for this book, but I don't want to go to the trouble of creating one.
St. George and St. Michael is a historical novel by George MacDonald and I wish he had written more like this. It includes prominent people from the English civil war in a story of a pretty typical MacDonald-ian hero and heroine. If you like MacDonald, I recommend it.
Here's a link to the free Kindle edition.
Some pertinent Wikipedia links: