der Mark

The House of La Marck, or von der Mark, began as a cadet line of the counts of Berg at Altena in Westphalia. Around 1198 Count Frederick of Berg-Altena built Mark Castle on the Ruhr; his son Adolf I founded Hamm in 1226 and made the County of Mark the family's seat. The counts broke free of Cologne by fighting for Brabant at the Battle of Worringen in 1288.

In 1368 Adolf III inherited Cleves and in 1394 united it with the Mark. Under John III the Peaceful the house formed the United Duchies in 1521, and his daughter Anne of Cleves married Henry VIII of England.

After the last duke died in 1609, the Treaty of Xanten assigned the Mark to Brandenburg in 1614. The last male count died in 1773 and the title passed to Arenberg.