As the third born son and with primogeniture in Saxe-Lauenburg Francis II made a military career in imperial services.

[2] This severed the anyway difficult relations with the estates of the duchy, which fought the ducal practice of growing indebtedness.

Francis II, who meanwhile had won his brother Maurice, by sharing the reign with him, lured Magnus into a trap and captured him later in 1585.

This forced Francis II into negotiations, which ended on 16 December 1585 with the constitutional act of the "Eternal Union" (German: Ewige Union) of the representatives of Saxe-Lauenburg's nobility and cities, Lauenburg upon Elbe and Ratzeburg, then altogether constituted as the estates of the duchy, led by the Land Marshall, a hereditary office held by the family von Bülow.

The relations between estates and duke improved since Francis II redeemed ducal pawns with money he had earned as imperial commander.

[3] Already earlier in 1585, after consultations with his brother Prince-Archbishop Henry, Francis II decreed a constitution (Kirchenordnung) for the Lutheran church of Saxe-Lauenburg.

[5] Starting in 1608 Francis extended the existing house to a castle with a large garden, called Franzgarten or Franzhof, in the end the name Franzhagen prevailed.