Graf von Nassau-Siegen, official titles: Graf zu Nassau, Vianden und Diez, Herr zu Breda, was since 1442 Count of Nassau-Siegen[note 2] (a part of the County of Nassau), of Vianden and of half Diez, and Lord of Breda [nl] and of the Lek [nl].

[2][3] John was a loyal servant of the Dukes of Burgundy in the Netherlands, who was still called up for military service even when he was well into his fifties, but he was not one of the closest noble advisors.

[4] John can best be characterised as a wealthy nobleman who faithfully fought in the campaigns for which he was called up; he was not known for spectacular deeds or revolutionary ideas.

[7] John was born in Breda Castle[8][note 3] on 1 August 1410[9][10][11][12][13] as the eldest son of Count Engelbert I of Nassau-Siegen and Lady Joanne of Polanen.

[4][9][12][14][15][16][17][18] In the period between his marriage and the death of his father, John lived in the house De Herberghe in the Reigerstraat in Breda.

[4] John was a loyal servant of the Dukes of Burgundy, who was still called up for military service even when he was well into his fifties, but he was not one of the closest noble advisors of Philip the Good and Charles the Bold.

[4] John can best be characterised as a wealthy nobleman who faithfully fought in the campaigns for which he was called up; he was not known for spectacular deeds or revolutionary ideas.

It was not a very politically sensitive office, although he could be assisted by archers on foot and horseback and received an annual payment of 600 Philippusguilders.

[note 5] Because of Philip the Good's interest in the Middle East, where his grandfather had suffered a grievous defeat at Nicopolis in 1396 that was still unreconciled, and the ever-increasing threat to Constantinople from the Ottoman Empire, John undertook a journey to the island of Rhodes on Philip's orders from May 1441 to February 1442, to see how the infidels could best be combated, but this led to nothing.

[5] In the lands of Philip the Good there was still a lot of unrest, like in the County of Holland, where in the 1440s the struggle between the Hooks and Cods had flared up again.

[5] More dangerous for Philip was the rebellion of the Flemish city of Ghent, which wanted to maintain its autonomy undiminished, and opposed the centralising policy of the Dukes of Burgundy.

[21] The citizens of Utrecht accepted the inevitable for the time being, but in Liège the unrest remained for many years, until in 1465 it came to an armed outburst.

[24] But this led to a conflict with his niece Ottilie of Nassau-Siegen, who also claimed her father part's of the County of Diez as her inheritance.

[13][note 7] The conflict was complicated further due to the fact that another part of the County of Diez belonged to Ottilie's father-in-law Count Philip the Elder of Katzenelnbogen.

John received the office of Marshal of Westphalia[note 8] in gratitude from the archbishop, but exchanged it for pledged Rhine tolls in 1455.

[26] Approximately midway between their possessions in the Netherlands and their counties in Germany the Counts of Nassau owned a house in the city of Cologne (das achte Haus von der Goltgassenecken nach St. Cunibert hin), which made the connection between the two areas easier for them.

During John's long absence, however, von Bicken used the trust placed in him and his own power base in the Haiger Mark to repeatedly overstep his authority, to such an extent that he arrogated territorial lord rights to himself, in order to increase his family's still very considerable possessions.

The count's fixed income included the Mai und Herbst Bede [de], which were levied on land tenure.

This is shown by the fact that in 1472 the Emperor ordered John to question witnesses as his commissioner in the lawsuit in the Kammergericht between the citizens of Nauborn [de] and the city of Wetzlar.

In a summons to the Schöffen of Wetzlar – sent by Count Philip II of Nassau-Weilburg with John's letter of attorney – the hearings are mentioned to take place on 12 October in Siegen.

In any case, he received a so-called Butterbrief from Pope Sixtus IV (dated Rome 25 February 1472), which allowed the inhabitants of his cities and castles to consume butter during Lent, and milk food – apart from cheese – instead of oil, because they lived in a cold region, where no olive oil grew and hardly any fish was available.

[40] He freed the heerlijkheid of Breda from the feudal ties to the Margraviate of Antwerp and brought it directly under the Duchy of Brabant.

[41] Through his marriage to Lady Mary of Looz-Heinsberg, John obtained the heerlijkheden of Herstal, Vught, Gangelt, Waldfeucht and the Land of Millen [de], so that he possessed 1⁄4 of the Duchy of Jülich.

[43] Apparently this had no effect, because in 1471 or 1472 the Emperor ordered Duke Charles the Bold of Burgundy to settle on his behalf the dispute between Gerhard on the one hand and John and his wife Mary on the other.

[44] The dispute became more complicated when in 1472 Gerhard VII's son William married to Countess Elisabeth of Nassau-Saarbrücken, John II's eldest daughter, who had inherited her mother's possessions.

[42][45][46] In 1474, the Emperor withdrew the order to Charles the Bold and instead transferred the matter to Archbishop John II of Trier.

On 14 October 1463, the Emperor appointed Abbot Reinhard [de] of Fulda as his attorney and instructed him to summon both parties to a trial on his behalf, to interrogate them and to give judgment.

What is known is that the Emperor summoned John for the settlement of the inheritance dispute with his sister, because on 9 February 1467 Mary appointed attorneys for the trial.