The Ostend War, also called the Baltic War, was a conflict fought in 1633 and 1634 between the alliance of Sweden and the Confederated Principalities of Europe/United States of Europe and the League of Ostend. It began in September 1633 with the betrayal of the Dutch fleet by the English and French at Dunkirk. It ended with the Congress of Copenhagen, held in in June of 1634, though the final battle was the Battle of Copenhagen, fought the previous month. The Ostend War can be considered as both a conflict in its own right, and as the final action in the NTL's version of the Thirty Years' War.