The Treaty of Frankfurt,[1] also known as the Truce of Frankfurt,[2] was a formal agreement of peace between Charles V, Holy Roman Emperor and Protestants on 19 April 1539. The parties met at Frankfurt-on-the-Main,[3] and the Lutherans were represented by Philip Melanchthon.[4] The treaty stated that the emperor would not take any violent actions against the Protestants, who had formed an alliance known as the Schmalkaldic League, for fifteen months starting 1 May;[3] during this time both parties could try to resolve the differences in their confessions. As a result of this peace, the Schmalkaldic League lost the protection of France.[3]