Martin Bucer’s De vera et falsa caenae dominicae administratione marks the collapse of his hopes for a negotiated settlement of the Reformation in Germany. He completed the work in March 1546 as fresh negotiations between Catholic and Protestant theologians reached an impasse in Regensburg, as the second session of the Council of Trent was meeting, and as Charles V prepared to make war on the Protestant League of Schmalkalden. At one level the work deals with the church’s authority to regulate the celebration of the Lord’s Supper, but at a more fundamental level it challenges moderate Catholics such as the humanist scholar Bartholomaeus Latomus to decide whether their ultimate loyalties lie with pope and council or with Christ and his Gospel.