The Duchy of Lower Lorraine encompassed part of modern-day Belgium and the Netherlands. It was closely tied to the Duchy of Upper Lorraine and the County of Boulogne. It was a major participant in the First Crusade; Godfrey of Bouillon later became the first King of Jerusalem (although he actually took the title "Defender of the Holy Sepulchre").
Within Lower Lorraine was the County of Bouillon; its counts were often simultaneously Dukes of Lower Lorraine, and after the death of Godfrey of Bouillon the County passed through numerous hands throughout the centuries.
