Martin V, né Otto di Colonna (1368 - February 20, 1431), pope from 1417 to 1431, was elected on St Martin's day at the Council of Constance by a conclave consisting of twenty-three cardinals and thirty delegates of the council, which after deposing John XXIII, had long experienced much perplexity from the conflicting claims of Gregory XII and Benedict XIII. This election effectively ended the Great Schism of the West.

The son of Agapito Colonna and Caterina Conti, born about 1368, he belonged to one of the oldest and most distinguished families of Rome, became apostolic protonotary under Urban VI, was created cardinal-deacon by Innocent VII, and in 1410 was the delegate of Alexander V to hear the appeal which had been taken in that year to the Papacy by Jan Hus.

He was justly esteemed for his moderation, learning, uprightness and business capacity, but he failed to achieve, as he might have done, the honour of being a reforming pope. His first act after his election was to publish a brief confirming all the regulations made by his predecessors with regard to the papal chancery, - regulations which had long been the suubject of just complaint. When the "nations" of the council pressed their plans for reform, Martin submitted a counter scheme, and ultimately entered into negotiations for separate concordats, for the most part vague and illusory, with Germany, England, and France.

He left Constance at the close of the council (May 1418), but travelled slowly through Italy, lingered at Florence, and did not venture to enter Rome until September 1420, when his first task was to seek to restore it to the prosperity and order to which it had become a stranger. In accordance with the decree of Constance, confirmed by himself, ordering that councils should be held every five years, he in 1423 summoned the council which met at Pavia and afterwards at Siena; it was somewhat poorly attended, and in this circumstance gave the pope a pretext for dissolving it as soon as it had come to the resolution that "internal church union by reform ought to take precedence of external union". It was prorogued for seven years, and then met at Basel; shortly after its opening Martin died of apoplexy, on February 20, 1431.

text from the 9th edition of an unnamed encyclopedia