In 1477, twenty-four years after the fall of the capital city of the Byzantine state, patriarch Maximos III of Constantinople addressed a circular to Christians “wherever they are under the rule of Our Lord and as far as Rome”. This book provides an edition and analysis of this unpublished document. The first chapter presents the text in facsimile and explores issues of its transmission. The second chapter presents the historical context: the events following the Fall and, mainly, the shift that occurred in the relations between the Patriarchate and the Porte owing to an initiative in 1474, involving the author of the circular. The third chapter is a critical edition of the text, while the fourth focuses on the regulations announced by the circular and promoted by Maximos III. These concern the inner life of the Orthodox Church as well as the life of Christians who were henceforth to live under the yoke of Ottoman rule.