Pomerania became a duchy of the Holy Roman Empire in 1181 when Bogislaw I swore his allegiance to Frederick I (Barbarosa), the German King and Roman Emperor. Thus began a Greif dynasty that continued for the next four centuries, with the crown passed down from generation to generation through inheritance. The last Pomeranian Duke was Bogislaw XIV who reigned until his death in 1637. With no one to inherit the crown, the electors of Brandenburg assumed control of Pomerania. During the 13th century, surnames began appearing and by 1400 they were in fairly common use throughout Germany.
In the twelfth and thirteenth centuries, tens of thousands of immigrants from the Rhineland, Westfalen, Niedersachsen, Holstein, Mecklenburg and Holland colonized Pomerania, establishing German villages among the Wend inhabitants and introducing trade. The immigrants, who were welcomed by the Pomeranian Dukes, provided the necessary skills and tools needed to clear the forests, drain the marshes, build dikes and roads, and farm the land. They introduced the iron plow and the 3-field rotation system of farming. Eventually, the German language and culture dominated the country and by the 1400's the Wends of Pomerania disappeared completely as a result of intermarriage.
The Church figured prominently in the early colonization with various ecclesiastical institutions receiving or buying vast areas. The Cistercians, the most prominent monastic order, established monasteries as early as the 1170's in Pomerania. One, the monastery of Kolbatz, acquired huge land holdings in Hinterpommern and by 1313, owned 53 villages. Intermixed among these possessions were the large estates of the princes and nobles, including both the native Slavs and the German knights who began arriving about 1235.
Pomerania, like the other German states, was greatly affected by the Reformation. Lutheranism took root in Pomerania in 1525 when Stralsund adopted Martin Luther's teaching. Nine years later, the Lutheran Church of Pomerania was established when the Diet at Treptow on the Rega prepared the basis for its formation. A plattdeutsch (low German) version of the bible was printed the same year and in 1536, the dukes of Pommern accepted the Lutheran faith. However, the hostility between the Catholics and the Protestants continued unabated despite the Peace of Augsburg in 1555 which was intended to settle the religious issue in Germany. In 1618, the Thirty Years War began primarily as a civil war between the two religious factions. In the summer of 1630, the war took on a political objective when Sweden entered the war. King Gustavus Adolphus, a Protestant, was concerned about the growing power of the Roman Emperor Ferdinand. The war continued for another 18 years until 1648 when the Treaty of Westphalia was signed. As compensation for its role in the war, Sweden was awarded control over Stettin and Vorpommern. Brandenburg retained control of Hinterpommern.
The Thirty Years War took a heavy toll in Pomerania with possibly one-third of its people killed and whole villages and farms completely destroyed. In the early 1700's, Pomerania again became the battleground for conflicts between Russia and Sweden. It ended in 1720 with the Treaty of Stockholm, which ceded part of Hither Pomerania as far as the Peene River to Brandenburg-Prussia. Following the defeat of Napoleon, the Congress of Vienna gave the remaining part of Swedish Pomerania to Prussia in 1815.
When King Wilhelm I became the first emperor of a united Germany in 1871, Prussia had become a powerful military nation that occupied the northern two thirds of Germany. It extended from the Netherlands and Belgium on the west to Russia on the east. In 1945, after World War II, Prussia ceased to exist as a German state and Pomerania was partitioned again at the Oder River. Hinterpommern and Stettin (now called Szczecin) became part of Poland and all of the Germans fled or were expelled from their country. Vorpommern, the area west of the Oder-Neisse Rivers, became part of East Germany. In 1990, Vorpommern became part of the reunified Germany and was included in the state of Mecklenburg-Vorpommern.