King John appointed Nicholaa de la Haye sheriff of Lincolnshire at Newark Castle, making her one of the only women to hold the office of sheriff in her own right in medieval England.
On 18 October 1216, at Newark Castle, King John formally appointed Nicholaa de la Haye as sheriff of Lincolnshire, an office that placed her in charge of royal justice, tax collection, and military security across the entire county. This appointment came only days before the king's own death and at the height of the First Barons' War, when royal authority was under severe threat from rebel barons and the invading forces of Prince Louis of France.
The appointment was extraordinary for its era: shrieval office was almost universally held by men, and Nicholaa's selection reflected both her proven loyalty to the Angevin crown and her demonstrated competence, having already defended Lincoln Castle on the crown's behalf on a prior occasion in 1191. By naming her sheriff in her own right rather than merely as a deputy for a male relative, John effectively recognized a woman as the chief royal officer of a strategically vital county.
Historians consider this one of the most striking examples of female authority in Plantagenet England. It positioned Nicholaa to play a decisive role in the following year's Battle of Lincoln Fair (1217), when she held the castle against besieging rebel and French forces, an action credited with helping to secure the young Henry III's throne. Her appointment remains a touchstone in discussions of medieval women's access to formal political and military power.