Apologies for the double post.
"The Warrior Queen: The Life and Legend of Æthelflæd, Daughter of Alfred the Great" by Joanna Arman.
Yes, that is indeed the full convoluted title and just as it implies - it is a biography of Æthelflæd (870 - 918 A.D), the Queen of Mercia and daughter of Alfred the Great who after the death of her husband, defended her kingdom against the invasion by the Great Heathen Army. Yet despite this she was largely forgotten by history until relatively recently.
It's a pretty good book, well researched and everything. Not sure how interesting it'd be to anyone outside of England.