Background
He was born in Auxerre. He was a son of William II of Nevers and his wife Adelaide. The ancestry of his mother is unknown.
He was born in Auxerre. He was a son of William II of Nevers and his wife Adelaide. The ancestry of his mother is unknown.
Robert of Nevers, another brother, is only mentioned in a charter dating to 1134. Their sister Anne of Nevers was married with William VIII, Count of Auvergne, also known as "William the Old" (reign 1155–1182). He is recorded as co-signing legal decisions by his father in charter dating to 1121 and 1134.
Their struggle lasted from 1135 to 1154 and is known as The Anarchy.
William III joined Louis VII of France in the Second Crusade. On 21 August 1148, his father died and William III succeeded him in Nevers and Auxerre.