In 1210 Valdemar led a second expedition eastwards, this time directed against heathen Prussia and Samland, the chief result of which was the subjection of Mestwin, duke of Pomerania, the leading chieftain in those parts.
In 1553 Duke Albert of Prussia, anxious to heal the differences in the Prussian church caused by the discussion of Osiander's doctrines, invited him to Konigsberg, and in the following year appointed him professor of divinity and president of the Samland diocese.
The fisheries in the lakes and haffs are of some importance; but the only mineral product of note is amber, which is found in the peninsula of Samland in greater abundance than in any other part of the world.
The Baltic amber or succinite is found as irregular nodules in a marine glauconitic sand, known as "blue earth," occurring in the Lower Oligocene strata of Samland in East Prussia, where it is now systematically mined.
Although amber is found along the shores of a large part of the Baltic and the North Sea, the great amber-producing country is the promontory of Samland.