Question: What is the name of the historical county, later duchy of the Holy Roman Empire, located in the Low Countries that  Adolf van Nieuwenaar worked for in the  Eighty Years' War?
Sentence (from "Guelders"): Guelders or Gueldres (Dutch: "Gelre" , German: "Geldern" ) is a historical county, later duchy of the Holy Roman Empire, located in the Low Countries.
Relevant evidence: Yes