treaty had been signed, the Knights and the Poles disputed a watermill in Lubicz, a strategic post that had been turned into a fortress. Vytautas was angered by the dispute and threatened to give up Palanga to the Knights if Poland did not surrender its claims to Lubicz. The Knights won this dispute. The treaty put an effective end to the Polish–Lithuanian cooperation against the Knights. The Teutonic Knights attempted to befriend the Lithuanians, offering a royal crown to Vytautas in hopes of breaking up the Polish–Lithuanian union. During the Lithuanian Civil War (1431–1435), Lithuanian Duke Švitrigaila was able to employ the Polish–Teutonic animosity for his own advantages – the Knights invaded Poland, starting the Polish–Teutonic War. The two states battled again during the Thirteen Years' War (1454–66), a civil war that tore Prussia in half. The agreement drew the Prussian–Lithuanian border roughly and imprecisely, resulting in local demarcation disputes. The border was redrawn with greater detail and precision in 1532 and 1545. The border survived without major changes until World War I. In 1919, the Treaty of Versailles detached the Klaipėda Region (Memel Territory) from Germany as a League of Nations mandate. Lithuania annexed the region in 1923. The southern portion of the border, with small modifications, still survives as the border between Lithuania and Kaliningrad Oblast, Russia. Notes References Peace treaties of Prussia Melno, Peace of Melno, Peace of 1422 in Europe 15th century in Lithuania Melno Melno Melno Lithuania–Russia border 15th century in the State of the Teutonic Order History of Samogitia 15th century in Poland