 During World War I, several battles were fought between the German and Russian armies in 1914 and 1915 in the area of Arys.The town was held by Russian troops for 20 days and heavily damaged.On July 11, 1920, the East Prussian plebiscite, mandated by the Versailles Treaty, was held in the District of Allenstein (now Olzstyn), which included Arys.