Æthelflæd (often spelled Aethelflaed) is one of the most underrated war leaders of the early Middle Ages—not because she swung an axe in the front line, but because she understood what actually beats raiders: fortifications, logistics, and timing. She was the daughter of Alfred the Great and the wife of Æthelred, the ruler of Mercia. As the Viking “Great Army” and its successors carved out the Danelaw, Mercia lived on the edge of collapse. When Æthelred grew ill and later died (around 911), Æthe