From Bohemia to the Thirty Years War 239rather than as a soldier, and he later carried out a number of important
diplomatic missions for Emperor Ferdinand II.
The second younger brother, Heinrich Julius, converted to
Catholicism in his youth, apparently in the hope of gaining a bish-
opric, but in the event he too entered Imperial service, in his case in
the army, fighting at the battle of the White Mountain and eventually
reaching the rank of field marshal. Nevertheless in 1628, in the middle
of this career, he married a daughter of the previous Lutheran elector of
Brandenburg, and their son, a future ruling duke of Sachsen-Lauenburg,
was brought up as a Protestant.
The third brother, Franz Karl, also fought in Bohemia, but on the other
side under Mansfeld, and he later raised a regiment for Christian IV of
Denmark, but after the latter’s defeat he enlisted in Wallenstein’s Impe-
rialist army. When the Protestant Gustavus Adolphus of Sweden entered
the war Franz Karl changed sides again to join him, staying with the
Protestants after the latter’s death but moving to the Saxon army, before
eventually converting to Catholicism and rejoining the Imperialists as a
general.
The youngest of the brothers, Franz Albrecht, joined the Imperial
army and served for many years, five of them under Wallenstein, despite
being a Protestant, before switching to Swedish service, where he was in
Gustavus Adolphus’s immediate entourage when the latter was killed
at the battle of Lützen. He then became second-in-command of Elector
Johann Georg’s Saxon army, until he was taken prisoner by the Imperial-
ists at the time of Wallenstein’s assassination, but after a relatively short
time he re-enlisted with his captors, continuing to serve the emperor
until his death in action almost ten years later.
In contrast three other younger sons, the brothers of the ruling
duke of Sachsen-Weimar, all became soldiers but remained Protestant
and stayed firmly in the anti-Habsburg camp, although Bernhard, the
youngest and most famous of them, eventually took his private army
into the service of Catholic France and was involved in a number of
attempts to secure a principality for himself, before falling ill and dying
on campaign. In Mansfeld’s case the lack of an inheritance likewise led
him into a career as a soldier of fortune, and although he was brought
up a Catholic and first enlisted with the emperor he then went over
to the Protestant Union, before going on to serve in turn the Catholic
duke of Savoy, the Protestant Bohemians, the Calvinist Friedrich of the
Palatinate, and the Lutheran Christian IV of Denmark.
The significant thing about younger sons was that they had rela-
tively little to lose, whereas ruling princes and their prospective heirs,