Guelders or Gueldres (Dutch: Gelre, German: Geldern) is a historical county, later duchy of the Holy Roman Empire, located in the Low Countries. The duchy was named after the town of Geldern (Gelder) in present-day Germany. Though the present province of Gelderland (English also Guelders) in the Netherlands occupies most of the area, the former duchy also comprised parts of the present Dutch province of Limburg as well as those territories in the present-day German state of North Rhine-Westphalia that were acquired by Prussia in 1713.
King Charles V abdicated in 1556 and decreed that the territories of the Burgundian Circle should be held by the Spanish Crown. When the northern Netherlands revolted against King Philip II of Spain in the Dutch Revolt, the three northern quarters of Gelderland joined the Union of Utrecht and became part of the United Provinces upon the 1581 Act of Abjuration, while only the Upper Quarter remained a part of the Spanish Netherlands.
At the Treaty of Utrecht, ending the War of the Spanish Succession in 1713, the Spanish Upper Quarter was again divided between Prussian Guelders (Geldern, Viersen, Horst, Venray), the United Provinces (Venlo, Montfort, Echt), Austria (Roermond, Niederkrüchten, Weert), and the Duchy of Jülich (Erkelenz). In 1795 Guelders was finally conquered and incorporated by the French First Republic, and partitioned between the départements of Roer and Meuse-Inférieure.