In 1619 Julius Henry, a certain Count of Altheim, and Charles Gonzaga founded the Order of the Conception (Italian: Ordine della Concezione), papally confirmed in 1624.

In 1623 the emperor conveyanced the lordship in Schlackenwerth (today Ostrov), which he had deprived from the Schlick family disgraced after participating in the insurgency defeated at the White Mountain, to Julius Henry.

[2][3] In 1629 Julius Henry was given supreme command over the imperial troops in Poland and in this function he negotiated a peace with John George I, Elector of Saxony in 1632, after the latter had refused to join a Lutheran wart coalition under Gustavus Adolphus.

Julius Henry successfully denied the competence of the imperial juridical commission which inquired against him, insisting on his status of immediate prince of the empire only to be judged by a college of his like.

In 1658 he forbade his vassals to pledge or else alienate fiefs, thus fighting the integration of manor estates in Saxe-Lauenburg into the monetary economies of the neighbouring city-states of Hamburg and Lübeck.

In 1659 Duke Julius Henry decreed in his general disposition (guide-lines for his government) "to also esteem the woodlands as heart and dwell [of revenues] of the Monarchy of Lower Saxony.

[5] In 1663 Julius Henry bought the castle in Hauenstein (Bohemia) from the von Schlick family, making it part of the ducal Schlackenwerth domain.