He was the son of Wertislaw, Lord of Rostock and Prince of the Obotrites.

King Canute VI of Denmark noticed this lack of support and used the opportunity to strengthen his position on the Baltic Sea coast.

In 1185, Nicholas I and Henry Borwin I had to accept Canute VI as their liege lord.

In return, Canute enfeoffed Nicholas I with the Lordship of Rostock.

On 25 May 1200, Nicholas I and Henry Borwin fought the Battle of Waschow, as part of a war against Count Adolf III of Holstein.