Henry was born on 7 January 1414[1][2][3][note 3] as the second son of Count Engelbert I of Nassau-Siegen and Lady Joanne of Polanen.

[10] On 30 July 1441, Frederick ordered Engelbert and Count Godfrey VIII of Eppstein-Münzenberg to accept the County of Diez as a fief from Archbishop James.

[11] On the same day the King informed Henry and Godfrey that he had granted Archbishop James the County of Diez as a fief together with all its appurtenances.

[14] A solution was apparently not reached there, because on 6 October 1444, following a complaint by James against Henry and John about the counties of Nassau and Diez and other fiefs, Frederick appointed Archbishop Dietrich of Mainz, as judge and gave him power of attorney to schedule a trial between the two parties on his behalf, and then to render a judgment.

On 24 July 1451 Frederick granted James, because Henry and Godfrey had not received the County of Diez from James, although more than a year and a day had elapsed since the royal letter was proclaimed to them, and also because Godfrey had pledged his share of the county without the King's and archbishop's consent, all the rights that had reverted to the King and the kingdom on account of the failure to take it as a fief and the pledging.

On the journey back, he died on 18 January 1451[note 5] at Radicofani in Tuscany, about 30 km north of Lake Bolsena.

[4] Henry was buried in the Collegiata (a collegiate church where the daily office of worship is maintained by a college of canons) in the small city of San Quirico d'Orcia, located about 25 km north of Radicofani.

[4][17][note 6] It is obvious to assume that Henry was on his way to Siena, about 25 km north of San Quirico d'Orcia, to make his appearance before King Frederick III.

That marriage between Frederick III and Princess Eleonor of Portugal had been mediated by the Bishop of Siena, Eneas Silvio Piccolomini, who later became Pope Pius II.

[4] The heavily worn tombstone shows in bas-relief a warrior in armour (chain mail, sword and dagger), except for the head, whose luxuriant hair is covered with a beret instead of a helmet.

Later, they did not even refrain from building a wall against the head-end as a support for the stairs to a new pulpit, which was closed by an iron gate that conveniently was hammered into the tombstone.

The aforementioned visitor, however, was able to find the original text of the epitaph in the church archives, which read as follows: 'HENRICO GERMANICO NASSOVII VIANDENII DIETCEQUE COMITI ILLUSTRI A JUBILEO REDEUNTI SACRUM OBIIT XV KAL FEBRUARII MCCCCLI' (English translation: 'Dedicated to the illustrious German Count Henry of Nassau, Vianden and Diez died on the return journey from the Jubilee 18 January 1451').

During a new restoration in 1946, necessary due to repair of war damage sustained in June 1944, a skeleton de grande proportioni was found in the choir, which is believed to be the remains of Henry.