For my newsletter, I interviewed Shelley Puhak, author of Dark Queens (Bloomsbury, 2022), a dual biography of the Merovingian queens Fredegund and Brunhild. She claims, and I haven't been able to find a counterexample, that this is the only example of women leading nations and going to war with each other. https://adamsnotes.substack.com/p/an-interview-with-shelley-puhak-author