The fourth Lateran council (twelfth ecumenical), convened by Pope Innocent III.
But these declarations as to the superiority of an ecumenical council never attained legal validity, in spite of their defence by Pierre d'Ailly and Gerson.
A compromise was arranged by Sigismund, who had been crowned emperor at Rome on the 31st of May 1433, by which the pope recalled the bull of dissolution, and, reserving the rights of the Holy See, acknowledged the council as ecumenical (15th of December 1 433).
Emanating from an assembly without a head, which could not possibly be an ecumenical council without the assent of one of the popes (of whom one was necessarily the legitimate pope) - enacted, in opposition to the cardinals, by a majority of persons for the most part unqualified, and in a fashion which was thus distinctly different from that of the old of John councils - they can only be regarded as a coup de XXIII.
The " Ecumenical Missionary Conference," held at New York in April 1900, was an astonishing revelation to the American public of the greatness of missions generally and of the missions of their own churches in particular.