The Siege of Niemcza took place during three weeks in August 1017 as part of the German-Polish War (1002–1018), when the forces of the Holy Roman Emperor Henry II besieged the town of Niemcza controlled by the Polish ruler Boleslaw Chrobry. Despite the aid of Bohemian and Veletian allies the German attack was ultimately unsuccessful, according to German chronicler Thietmar of Merseburg due to the resilience of the defenders, the arrival of reinforcements which managed to break into the city, and the illness among the imperial army. The failure of the siege marked the end of the German emperor's campaign in Poland and led him to agree to the Peace of Bautzen (1018) which left Lusatia and Upper Lusatia (Milsko) under Polish control.