Henry Borwin I was a son of Pribislaw and his wife, Woizlava of Pomerania, daughter of Wartislaw I, Duke of Pomerania. Pribislav was an Obotrite prince and was the first Lord of Mecklenburg. He died on 30 December 1178 of a wound he received during a tournament at the court of Henry the Lion in Lüneburg, and Henry Borwin I succeeded him as Lord of Mecklenburg. Shortly before Pribislav's death, Henry Borwin I married Matilda, a daughter of Henry the Lion.
For several years, Henry Borwin I fought a war with his cousin Nicholas I. His father-in-law was unable to assist him during this war. This lack of outside assistance attracted the attention of King Canute VI of Denmark, who used the situation to expand his position on the Baltic Sea coast. The Danes took Henry Borwin I prisoner. He had to cede Rostock to Denmark and accept Canute VI as his liege lord. In 1200, Canute returned Rostock to him as a fief. In 1202, he fought on the Danish side in the Battle of Stellau. The Danes won, and Henry Borwin was rewarded with two more fiefs: Gadebusch and Ratzeburg.
In 1218 and 1219, he assisted in the Danish conquest of Estonia, and, from 1225 to 1227, he assisted them in a war against Schauenburg.
Henry Borwin I revived the cities of Rostock and Wismar and founded the abbeys of Dobbertin, Tempzin and Sonnenkamp.
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