I have heard the story of Eleanor of Aquitaine on the Second Crusade, riding with her royal ladies in the guise of Amazons. Now, thanks to Allen and Amt's The Crusades: a reader, I finally see the original source of the story. It's a little vaguer than I expected, but still charming. A Byzantine annalist named Niketas Choniates says:
But while the Emperor governed the empire in this fashion, a cloud of enemies, a dreadful death-dealing pestilence, fell upon the Roman borders. I speak of the campaign of the Germans, joined by other kindred nations. Females were numbered among them riding horseback in the manner of men, not on the coverlets sidesaddle but unashamedly astride, and bearing lances and weapons as men do; dressed in masculine garb they conveyed a wholly martial appearance, more mannish than the Amazons. One stood out from the rest as another Penthesilea and from the embroidered gold which ran around the hem and fringes of her garment was called Goldfoot.Image: a fantasy portrait of Eleanor, borrowed from here.