The
Treaty of Melno (; ) or
Treaty of Lake Melno was a
peace treaty ending the
Gollub War. It was signed on September 27, 1422, between the
Teutonic Knights and an alliance of the
Kingdom of Poland and the
Grand Duchy of Lithuania at
Lake Melno (German:
Melnosee,
Meldensee; Polish:
Jezioro Melno), east of Graudenz (
Grudziadz). The treaty resolved territorial disputes between the Knights and Lithuania regarding
Samogitia, which had dragged on since 1382, and determined the Prussian–Lithuanian border, which afterwards remained unchanged for about 500 years. A portion of the original border partially survives as the border between the
Republic of Lithuania and
Kaliningrad Oblast, Russia, making it one of the most stable national borders in Europe.