It has been long established that the House of Brunswick has held and protected the regional Grand Commanderies throughout Europe. The Dukes of Brunswick have served as regional Grand Commanders, and as National Grand Masters (and Empire wide in Prussia) over the Templars. This has remained since the time of Henry the Lion and His son Otto IV who was Holy Roman Emperor and was the rival King of Burgandy. For more than 900 years the Imperial Princely House of Brunswick has been established Gothian Templar Nobility. In the year 1303 at Süpplingenburg, Braunschweig ,Otto von Brunswick is listed as Comte of the Knights Templars. The House headquarters at Gottingen and later at Wolfenbuettel has served as a Grand Priory for the Templars in Eastern and Western Europe.
More on this topic (link to Oels commandery article)