I thought Basel rang a bell...
from
http://www.newadvent.org/cathen/02334b.htm...Whether Basle is to be regarded as a general council, and if so, in what sense, has been often warmly discussed. The extreme Gallicans (e.g. Edmund Richer, Hist. Concil. Gen., III, vii) contend that it should be reckoned as cuмenical from its beginning (1431) till its end in Lausanne (1449); while the moderate writers of the Gallican school (e.g. Nat. Alexander, IX, pp. 433-599) admit that after the appearance of the Bull of Eugene IV (18 September, 1437) transferring the council to Ferrara, the proceedings at Basle can be regarded only as the work of a schismatical conventicle. On the other hand, writers like Bellarmine (De Concil., I, vii), Roncaglia, and Holstein absolutely refuse to number Basle among the general councils of the Church on account of the small number of bishops in attendance at the beginning, and the subsequent rebellious attitude in face of the papal decrees of dissolution. The true opinion seems to be that put forward by Hefele (Conciliengesch., 2d ed., I, 63-99) that the assembly at Basle may be regarded as ecuмenical from the beginning until the Bull "Doctoris Gentium" (18 September, 1437) transferred its sessions to Ferrera, and that the decrees passed during that period regarding the extirpation of heresy, the establishment of peace among Christian nations, and the reform of the Church, if they are not prejudicial to the Apostolic See, may be considered as the decrees of a general council...