It was convoked as the Council of Basel by Pope Martin V shortly before his death in February 1431 and took place in the context of the Hussite Wars in Bohemia and the rise of the Ottoman Empire.

The initial location in the Prince-Bishopric of Basel reflected the desire among parties seeking reform to meet outside territories directly controlled by the Pope, the Emperor[disputed – discuss] or the kings of Aragon and France, whose influences the council hoped to avoid.

The next council fell due at the expiration of seven years in 1431; Martin V duly convoked it for this date to the town of Basel and selected to preside over it the cardinal Julian Cesarini, a well-respected prelate.

[3] The Council had meanwhile successfully negotiated reunification with several Eastern Churches, reaching agreements on such matters as the Western insertion of the phrase "Filioque" to the Nicene-Constantinopolitan Creed, the definition and number of the sacraments, and the doctrine of Purgatory.

On 6 July 1439 the union was proclaimed (in both Latin and Greek) in the document Laetentur Caeli ("Let the Heavens Rejoice") which was signed by Pope Eugene and by the Byzantine Emperor John VIII Palaiologos.

Only one Eastern Bishop refused to accept the union, Mark of Ephesus, who became the leader of opposition back in Byzantium; the Serbian patriarch did not even attend the council.

The Russian Orthodox Church, upon learning of the union, angrily rejected it and ousted any prelate who was even remotely sympathetic to it, declaring itself autocephalous (i.e., autonomous).

[5] [The council] also declares that the apostolic prohibition, to abstain from what has been sacrificed to idols and from blood and from what is strangled, was suited to that time when a single church was rising from Jews and gentiles, who previously lived with different ceremonies and customs.

Doctors of theology, masters and representatives of chapters, monks and clerks of inferior orders constantly outnumbered the prelates in it, and the influence of the superior clergy had less weight because instead of being separated into "nations", as at Constance, the fathers divided themselves according to their tastes or aptitudes into four large committees or "deputations" (deputationes).

Nicholas of Cusa was a member of the delegation sent to Constantinople with the pope's approval to bring back the Byzantine emperor and his representatives to the Council of Florence of 1439.

Pope Eugene IV, Martin V's successor, lost hope that the council could be useful owing to the progress of heresy, the reported troubles in Germany, the war that had lately broken out between the dukes of Austria and Burgundy, and finally, the small number of fathers who had responded to the summons of Martin V. That opinion and his desire to preside over the council in person, induced him to recall the fathers from Germany, as his poor health made it difficult for him to go.

They held sessions, promulgated decrees, interfered in the government of the papal countship of Venaissin, treated with the Hussites, and, as representatives of the universal Church, presumed to impose laws upon the sovereign pontiff himself.

[1] Eugene IV resolved to resist the Council's claim of supremacy, but he did not dare openly to repudiate the conciliar doctrine considered by many to be the actual foundation of the authority of the popes before the schism.

[1] Abandoned by a number of his cardinals, condemned by most of the powers, deprived of his dominions by condottieri who shamelessly invoked the authority of the council, the pope made concession after concession and ended on 15 December 1433 with a pitiable surrender of all the points at issue in a papal bull, the terms of which were dictated by the fathers of Basel, that is, by declaring his bull of dissolution null and void and recognising that the synod as legitimately assembled throughout.

Furthermore, the difficulties of all kinds against which Eugene had to contend, such as the insurrection at Rome, which forced him to escape by means of the Tiber, lying in the bottom of a boat, left him at first little chance of resisting the enterprises of the council.

Other conciliar decrees severely limited the jurisdiction of the court of Rome and even made rules for the election of popes and the constitution of the Sacred College.

[9] Finally, they investigated and judged numbers of private cases, lawsuits between prelates, members of religious orders and holders of benefices, thus themselves committing one of the serious abuses for which they had criticized the court of Rome.

[7] The Council clarified the Latin dogma of papal primacy: "We likewise define that the holy Apostolic See, and the Roman Pontiff, hold the primacy throughout the entire world; and that the Roman Pontiff himself is the successor of blessed Peter, the chief of the Apostles, and the true vicar of Christ, and that he is the head of the entire Church, and the father and teacher of all Christians; and that full power was given to him in blessed Peter by our Lord Jesus Christ, to feed, rule, and govern the universal Church.

He consented to come with the principal representatives of the Byzantine Church to some place in the West where the union could be concluded in the presence of the pope and of the Latin council.

By a bull dated 18 September 1437, Pope Eugene again pronounced the dissolution of the Council of Basel and summoned the fathers to Ferrara in the Po Valley.

The early sessions lasted until 17 July 1438 with each theological issue of the East–West Schism (1054) hotly debated, including the Processions of the Holy Spirit, the Filioque clause in the Nicene Creed, purgatory, and papal primacy.

On 6 July 1439 an agreement (Laetentur Caeli) was signed by all the Eastern bishops but one, Mark of Ephesus, delegate for the Patriarch of Alexandria, who, contrary to the views of all others, held that Rome continued in both heresy and schism.

The signature of this agreement for the union of the Latins and the Byzantines encouraged Pope Eugenius to announce the good news to the Coptic Christians, and invite them to send a delegation to Florence.

The council went on (in spite of the intervention of most of the powers) to pronounce Eugene IV deposed (25 June 1439), giving rise to a new schism by electing (4 November 1439) duke Amadeus VIII of Savoy, as (anti)pope, who took the name of Felix V.[7] This schism lasted fully ten years, although the antipope found few adherents outside of his own hereditary states, those of Alfonso V of Aragon, of the Swiss confederation and of certain universities.

Finally, in 1447, Frederick III, Holy Roman Emperor, after negotiations with Eugene, commanded the burgomaster of Basel not to allow the presence of the council any longer in the imperial city.

Eugene IV died on 23 February 1447, and the council at Lausanne, to save appearances, gave their support to his successor, Pope Nicholas V, who had already been governing the Church for two years.

Perhaps the council's most important historical legacy was the lectures on Greek classical literature given in Florence by many of the delegates from Constantinople, including the neoplatonist Gemistus Pletho.