Zadar had come under the rule of Sigmund of Luxembourg after the death of Louis I of Hungary and Croatia in 1382, and eventually comes into the possession of Ladislaus of Naples, who, witnessing his loss of influence in Dalmatia, on July 31, 1409, sells Zadar and his dynasty's rights to Dalmatia to Venice for one hundred thousand ducats.

This is part of his attempts to gain allies in the upcoming war against the Republic of Florence, caused by his expansion in central Italy and his alliance with Paolo Guinigi, lord of Lucca, a traditional enemy of the Florentines.

Venice has therefore obtained control over Zadar without a fight, but is confronted by the resistance and tensions of important Zadar families.

These attempts are met with persecution and confiscation.

Venice installs nobility to govern the area, for example, Count Filippo Stipanov in Zadar.

Zadar remains the administrative seat of Dalmatia, but this time under the rule of Venice, which will soon expand over all of Dalmatia from Istria to Albania, barring …

…the Republic of Ragusa.

This move by the Venetians had been made in response to the threatening expansion of the late Gian Galeazzo Visconti, Duke of Milan.

Control over the northeast main land routes is also a necessity for the safety of Venetian trade.

Avignonese "antipope" Benedict XIII has resisted the pressure on him to abdicate, arguing that abdication is uncanonical.

Pointing out that he is the only surviving cardinal from before the Great Schism, Benedict concludes that his vote is the only one that is certainly valid, and he would, of course, choose himself.

The obstructive tactics of Benedict and the Roman claimant, Gregory XII, cause the cardinals of Rome and Avignon to despair of getting any cooperation from them toward unity.

Abandoning both, the cardinals summon the Council of Pisa in 1409, a general assembly of the Roman Catholic Church, recognized by neither claimant.

Ladislaus invades Tuscany in 1409, capturing Cortona and …

…the island of Elba from Iacopo II Appiani.

Florence hires the condottiere Braccio da Montone, who defeats Ladislaus, and he is forced to retreat.

Ladislaus has not abandoned his aims in northern Italy, however, and takes advantage of the presence of Pope Gregory XII in Gaeta.

The Republics of Siena and Florence and the powerful cardinal Baldassarre Cossa, fearing the aims of Ladislaus, ally against him.

Antipope Alexander V excommunicates him, and calls Louis II of Anjou back to Italy to conquer Naples.

Louis arrives in late July 1409 with fifteen hundred cavalry and is invested with the Neapolitan crown.

The allies' troops, under Muzio Attendolo, Braccio da Montone and other condottieri, invade the Papal lands under Ladislaus' control and move to Rome; Orsini, left by Ladislaus to protect the city, defects to them with two thousand men.

However, the allies capture only the Vatican and the Trastevere quarter.

Cardinal Cossa and Louis leave the siege to their condottieri, and move to northern Italy and Provence in search of further support.

Ladislaus has taken advantage of an anti-French revolt in Genoa to gain the support of this city in 1410.

Rome falls on January 2, and the allies do not score any other notable results.

Louis's fleet, carrying new troops from Provence, is intercepted on May 16 or 17 and partly destroyed off the Tuscan coast, with the loss of six thousand men and Louis's treasure (for a value of six hundred thousand ducats), which falls into the hands of Ladislaus.

The churchmen present at Pisa had enunciated the conciliarist theory that councils are superior to the pope, and had thereupon deposed both popes as heretical and schismatic.

They had then complicated the schism by electing a third claimant to the papacy, who had taken the name Alexander V, to be succeeded following his death eleven months later by the election, on May 25, 1410, of forty-year-old Baldassare Cossa, who had studied law and serves as an administrator in the Curia while endeavoring to end the schism; Cossa takes the reign title John XXIII; he had been ordained priest only one day earlier.

The Pisan claimants receive the support of most of Latin Christendom, but the schism continues.

John XXIII proclaims a crusade against Ladislaus and authorizes the sale of indulgences to finance it.