Nassau-Dillenburg

Nassau-Dillenburg was a county of the Holy Roman Empire centered on Dillenburg north of the Lahn. After the division of Nassau in 1255, the lands passed to the Ottonian branch; Dillenburg became a separate county in 1303 and was reunited with Nassau-Siegen in 1328.

In 1544 William of Nassau-Dillenburg's son William inherited the Principality of Orange and later led the Dutch Revolt. His brother John VI ruled at Dillenburg and was a principal author of the Union of Utrecht. After John's death in 1606, his lands were divided among his sons.