Soběslav I, Duke of Bohemia

Soběslav I of Bohemia
Duke of Bohemia
Image of Duke Soběslav
Duke of Bohemia
Reign	12 April 1125 – 14 February 1140
Predecessor	Vladislaus I
Successor	Vladislaus II
Born	c. 1075
Died	14 February 1140(1140-02-14) (aged 64–65)
Spouse	Adelaide of Hungary
Issue	Wenceslaus II Udalrich II Maria of Bohemia Soběslav II Vladislaus
House	Přemyslid dynasty
Father	Vratislaus II
Mother	Świętosława of Poland
Religion	Roman Catholicism

Soběslav I (also "Sobeslaus"; c.1075 – 14 February 1140) was Duke of Bohemia from 1125 until his death. He was a member of the Přemyslid dynasty, the youngest son of Vratislaus II (d. 1092), by his third wife Świętosława of Poland.

Soběslav is first documented about 1107, when he and his elder brother Duke Bořivoj II were expelled by their Přemyslid relative Svatopluk of Olomouc and fled to the court of their maternal cousin Duke Bolesław III Wrymouth of Poland. After Svatopluk was assassinated during the Battle of Głogów in 1109, Bořivoj's attempts to regain the Bohemian throne failed. In the following fratricidal war that followed the battle, Bořivoj's younger brother Vladislaus I prevailed, backed by King Henry V of Germany. Later the brothers reconciled and Soběslav was vested with rule at Brno and Znojmo in Moravia from 1115 until 1123, when tensions between the brothers rose again and Soběslav was once more expelled.

Nevertheless, as the last surviving son of Vratislaus II, he succeeded to the ducal throne after Duke Vladislaus' death in 1125. From the beginning, his rule was contested by Otto II the Black, the younger brother of Svatopluk, who gained support not only from Vladislaus's widow Richeza of Berg, but also from King Lothair III of Germany. Soběslav therefore was an adversary of the German monarchy throughout his reign and began by using the divisiveness of the 1125 election of King Lothair against rival Duke Frederick II of Swabia to further Bohemian independence.