Why was Frederick William unable to gain a direct pathway to the Baltic Sea?

Frederick William, the Elector of Brandenburg, was unable to secure a direct, permanent pathway to the Baltic Sea primarily due to the geopolitical dominance of Sweden and the intervention of other European powers during the 17th century.12

Following the Peace of Westphalia in 1648, Sweden gained control of western Pomerania and the vital Oder estuary, including the harbor of Stettin, which blocked Brandenburg’s direct access to the sea. Although Frederick William attempted to acquire these territories through military campaigns—such as during the First Northern War—his efforts were repeatedly thwarted.13

Even when he successfully drove Swedish forces from western Pomerania, international pressure, particularly from France, forced him to relinquish these conquests. Consequently, while he secured full sovereignty over the Duchy of Prussia via the Treaty of Oliva in 1660, he remained unable to consolidate a contiguous, sovereign corridor to the Baltic coast during his reign.12