Lastly, there is the remarkable arrangement for securing the validity of the charter. Let us look at this closely.[559] We should first notice that the Empress describes it, not as a charter, but as a "convencio et donatio." Now this "convencio" is a striking term, for it virtually denotes a treaty between two contracting powers. This conception of treaty relations between the Crown and its subjects is one of the marked peculiarities of this singular reign. It is clearly foreshadowed in those noteworthy charters which the powerful Miles of Gloucester secured from Stephen at his accession, and it meets us again in the negotiations between the youthful Henry of Anjou, posing as the heir to the crown, and the great nobles, towards the close of this same reign. It is in strict accordance with this idea that we here find the Empress naming those who were to be her sureties for her observance of this "convencio," precisely as was done in the case of a treaty between sovereign powers.[560] The exact part which the King of France was to play in this transaction is not as clear as could be wished, but the expression "capere in manu" is of course equivalent to his becoming her "manucaptor," and "tenere" is here used in the sense of "to hold good."[561] The closing words in which "the Lady of England" declared that all the Church of Christ then beneath her sway shall undertake to be responsible for her keeping faith, present a striking picture: but yet more vivid, in its dramatic intensity, is that of the undaunted Empress, the would-be Queen of the English, standing in her water-girdled citadel, surrounded by her faithful followers, and playing, as it were, her last card, as she placed her hand, in token of her faith, in the grip of the Iron Earl.[562] It was only, indeed, the collapse, to all appearance, of her fortunes, that could have tempted Geoffrey to demand, or have induced the Empress to concede, terms so preposterously high. The fact that she was hoping, at this moment, to allure her husband to her side, that he might join her in a crowning effort, explains her eagerness to secure allies, at the cost of whatever sacrifice, and also, in consequence, the anxiety of those allies to bind her to her promises hard and fast. It further throws light on the constant reference throughout this charter to Geoffrey of Anjou and his son.