This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Council of Basel began as the logical next step after Constance, which had ended the Western Schism and asserted, in doing so, that a general council could sit in judgment above a pope when the church's unity was at stake. Basel was meant to keep building on that claim. Instead it became the event that broke it.
Pope Eugene IV tried to dissolve the council within months of its opening, then tried again in 1437 to move it to Ferrara, closer to his own control and to negotiations with the Eastern church he hoped to reunite with Rome. Both times, a majority at Basel refused to leave. What had been one council became two: a pope-recognized body that relocated to Ferrara and then Florence and did, eventually, produce a short-lived reunion agreement with the Byzantine church, and a rump assembly that stayed at Basel, kept insisting a council outranked a pope, and in 1439 elected its own pope, Felix V, to prove it.
Felix's resignation a decade later, in 1449, effectively ended the argument by attrition rather than by anyone conceding it. Conciliarism, the idea Basel had been built to defend, never again mounted a serious institutional challenge to papal authority in the way it had for over a century leading up to this council. Its arguments did not disappear, though. They resurfaced within a hundred years in Reformation debates over where church authority actually resides, made by reformers who had read the same Basel-era texts and drawn a very different conclusion about where that argument should have ended.