His brother Giordano, Lord of Genazzano, Capranica Prenestina, San Vito and Ciciliano, a Neapolitan General, Patrician of Naples in 1417, was shortly Prince of Salerno and Duke of Venosa from 3 August 1419, dying of plague on 16 August 1422, having married Mascia Annibaldi, who died in 1423, without issue, while his sister Paola was Lady of Piombino between 1441 and 1445.

His authority in Rome was represented by his brother Giordano, who had fought under Muzio Attendolo against the condottiero Braccio da Montone.

[5] Faced with competing plans for general reform offered by various nations, Martin V submitted a counter-scheme and entered into negotiations for separate concordats, for the most part vague and illusory, with the Holy Roman Empire, England, France and Spain.

Adherents of Jan Hus, who had been previously burned at the stake as a heretic by the council, adopted the practice of Communion under both kinds.

Bohemian and Moravian nobles responded that the sentence on Hus was unjust and insulting to their country, and promised to protect priests against episcopal prosecutions for heresy.

[6] In 1419 King Wenceslaus IV, who had resisted what he considered interference in his kingdom, commanded that all ejected Catholic beneficiaries should be reinstated in their offices and revenues.

Jan Želivský, an extreme anti-Catholic preacher of Prague, led a procession to the town hall, where under the leadership of Jan Žižka of Trocnov, a noble of southern Bohemia, the building was stormed and people found inside were thrown out of the windows on to the spears and swords of the processionists, and hacked to pieces.

On 1 March 1420, Pope Martin V issued a Bull inviting all Christians to unite in a crusade against the Wycliffites (Lollards), Hussites, and other heretics.

On 12 July 1420 the Pope conceded to attach an indulgence to anyone who would contribute to a crusade against the latter, which would be led by Sigismund, King of the Romans.

The following year, the combined Papal-Neapolitan army, led by Giacomo Caldora and Francesco Sforza, defeated him at the Battle of L'Aquila (2 June 1424); Braccio died a few days later.

[4] In the same year Martin obtained a reduction of the autonomy of the commune of Bologna, whose finances would be thenceforth under the authority of a papal treasurer.

[4] He also ended the war with Braccio da Montone in exchange for his recognition as vicar[4] and reconciled with the deposed John XXIII, to whom he gave the title of Cardinal of Tusculum.

[4] The excitement of the Church during the Hussite movement rendered the Jews apprehensive, and through Emperor Sigismund, they obtained from Pope Martin V various bulls (1418 and 1422) in which their former privileges were confirmed and in which he exhorted the friars to use moderate language.

A gathering, convoked by the Jews in Forlì, sent a deputation asking Pope Martin V to abolish the oppressive laws promulgated by Antipope Benedict XIII.

According to Burton, Martin authorized a crusade against Africa in 1418, and this, coupled with a later bull of Pope Eugene IV (1441), sanctioned the Portuguese trade in African slaves.

[P]olitical weakness compelled the Renaissance Papacy to adopt an acquiescent and unchallenging position when approached for requests for privileges in favour of these ventures.

"[18] During his permanence in Rome, Martin moved his residence from the Lateran to Santa Maria Maggiore and, from 1424, the Basilica of Santi Apostoli near the Palazzo Colonna.