The Battle of Ilawa was a battle that took place near the town of Iława (German: Eylau), on May 25, 1455, during the Thirteen Years' War. In the spring of 1455, the Teutonic Knights began a new campaign in Lower Prussia (the area of Königsberg), which had been controlled by Polish forces. The local population disliked the Poles, who had imposed high taxes, and supported the army headed by Grand Master Heinrich Reuss von Plauen.