"Godefridi et Balduini" are named as sons of "Ida comitisse Boloniensis" in the latter's charter for the soul of her husband. William of Tyre records "Godefridus Lotharingiæ dux" as brother of Baudouin and Eustache, and son of Comte Eustache and of Ida sister of Godefroi "Struma" Duke of Lotharingia. Designated heir by his maternal uncle, on the latter's death in 1076 he inherited the county of Verdun, the allods of Stenay and Mouzay, and the castle of Bouillon with its dependencies. The inheritance was disputed by many parties. Theoderic Bishop of Verdun seized the opportunity to end the hereditary succession in the county of Verdun by bestowing it on Matilda of Tuscany, who granted it to Albert III Comte de Namur as guardian of her interests in Lotharingia. The emperor conferred the duchy of Lotharingia on his infant son Konrad with Albert III Comte de Namur as vice-duke, although he did create Godefroi as Markgraf van Antwerpen.
When his predecessor Konrad Duke of Lower Lotharingia was crowned King of Germany in 1087, Godefroi de Boulogne was installed as GODEFROI IV Duke of Lower Lotharingia. He was known as "Godefroi de Bouillon", after the castle which he inherited from his mother's family and which became his centre of operations.
Leader of the First Crusade in 1096, he disposed of his properties to fund the expedition, although he retained the title duke. The crusading army reached Jerusalem 7 Jun 1099 and captured the city 15 Jul 1099. The electoral council chose him as ruler of Jerusalem 22 Jul 1099, and after considerable debate about the correct title to adopt, he became GODEFROI princeps of Jerusalem. 1