Since Augustus survived all his sons he was succeeded by his half-brother Julius Henry.

On his ascension Augustus moved Saxe-Lauenburg's capital from Neuhaus, whereto Francis II had moved it after the residential castle in Lauenburg upon Elbe (started in 1180–1182 by Bernhard, Count of Anhalt) had burnt down in 1616, towards Ratzeburg, where it remained since.

[1] During the Thirty Years' War Augustus always remained neutral, however, billeting and alimenting foreign troops marching through posed a heavy burden onto the ducal subjects.

On 5 March 1621 he married in Husum Elisabeth Sofie of Holstein-Gottorp (12 December 1599 – 25 November 1627), daughter of John Adolf, Duke of Holstein-Gottorp.

On 4 June 1633 he married, as his second wife, Catherine of Oldenburg (20 September 1582 – 29 February 1644), daughter of John VII, Count of Oldenburg.