[4] In March 1416, Count William raised the matter with Sigismund while the latter was the guest of the English king, Henry V of England, but was rejected; he angrily returned home.

In Hainaut, where female succession was long customary, Jacqueline was recognized as countess on 13 June, but in Holland and Zeeland her rights were controversial from the beginning.

On the advice of her mother, Jacqueline initially gave her uncle the title of Guardian and Defender of the County of Hainaut (Hüters und Verteidigers des Landes Hennegau) in order to forestall his ambitions.

[5] However, the German King Sigismund, who had already been against Jacqueline's rights since 1416, formally enfeoffed John III with the counties of his deceased brother and married him to his niece Elisabeth of Görlitz, Duchess of Luxembourg and widow of Anthony, Duke of Brabant, who died in the Battle of Agincourt in 1415.

[6] On 31 July 1417, two months after William II's death, the betrothal between Jacqueline and John IV took place, and the wedding was celebrated in The Hague on 10 March 1418.

The close relationship between the spouses required a papal dispensation, which, although granted in December 1417, was revoked in January 1418 in the Council of Constance due to the intrigues of Jacqueline's opponents, including King Sigismund of Luxembourg.

[7] In addition to this, the considerable financial problems of the young Duke John IV and his weak political leadership increased the conflicts inside the marriage.

The troops of uncle and niece met in the Battle of Gorkum in 1417; Jacqueline was victorious, but was forced to leave the major trading city of Dordrecht.

In addition, her marital status was again questioned thanks to her uncle, who claimed that without papal dispensation the union was annulled;[8] this caused even more misgivings for Jacqueline about how to maintain her marriage.

[11][12] In exchange, John III gave a monetary compensation to the couple and left them the County of Hainaut; however, this was a little consolation for Jacqueline, whose subjects of Holland, Zeeland and Friesland were released from their oath of allegiance under the terms of the treaty.

The Duke of Burgundy, John the Fearless, was assassinated in September 1419, and the French Dauphin Charles, brother of Jacqueline's first husband, was considered an accomplice and was therefore disinherited in 1420 under the Treaty of Troyes.

In February 1421 Jacqueline issued a statement where she stated that, because of the destructive behaviour of John IV of Brabant, she wanted the annulment of her marriage.

She asked Pope Martin V in Rome and Antipope Benedict XIII in Avignon to resolve her irregular marital status, but her uncle John III intervened against it.

[18] Jacqueline and Humphrey landed in Calais and by the end of November they entered Mons, where on 5 December the Duke of Gloucester was recognized as the sovereign Count of Hainaut.

Jacqueline escaped her imprisonment in Ghent disguised in men's clothing and fled to Schoonhoven and then Gouda, where she stayed with the leaders of the Hook faction.

In this matter, Humphrey did intervene, albeit with limited force; his efforts, however, had disastrous consequences for the English-Burgundian alliance that aided the English cause in France during the Hundred Years' War.

By this treaty, Jacqueline kept her titles of Countess of Holland, Zeeland and Hainaut, but the administration of her territories was placed in the hands of Philip, who was also appointed as her heir in case she died without children.