[2] The duke is known under many spellings (Swantepolk, Swantipolk, Svatopluk, Swietopelk, Swatopolk, Sviatopolk, Światopełek, Świętopełk, Swiãtopôłk), of which Domin(us) Zwantepolc(us) D(ux) Danceke[3] and Svantopelc Ducis Pomeranie[4] were used on seals.

His father had ruled over Eastern Pomerania (or Pomerelia) since about 1205 by appointment of the Polish high duke Władysław III Spindleshanks.

In 1218, Swietopelk took advantage of a revolt of local knights against Danish rule to occupy the Lands of Schlawe and Stolp.

On 23 November 1227, on the occasion of an assembly of Piast dukes in Gąsawa, Leszek was killed in an ambush set by Swietopelk II and perhaps Władysław, while Henry was severely wounded.

In 1233-34, Swietopelk II, with his brother Sambor, joined a crusading army along with Hermann Balk, Konrad I of Masovia, Henry the Bearded, and Władysław Odonic.

Sambor and Racibor were driven out from their lands and sought refuge and alliance first with Piast relatives in Greater Poland, later with the Teutonic Knights, a Christian military order waging a crusade against pagan Prussians.