After succeeding King Gundemar in 612, Sisebut ruled successfully for 9 years. While his was one of the shorter reigns of Visigothic Spain, Sisebut left an indelible mark on the land. Firstly, he launched a number of successful military campaigns against the residual Eastern Roman forces in southern Spain. More importantly however, were his religious beliefs. A devout Chalcedonian Christian, he believed in the true union of humanity and divinity in the singular body of Jesus Christ. Called dyohypostasis, this highly divisive religious theory was codified in 451 by the Council of Chalcedon, hence Chalcedonian Christianity. Not only did this cause friction with his neighbor Adaloald, the Lombard King of Italy, as demonstrated in a letter he wrote on the Arian heresy to Adaloald’s mother Theodelind, but it also impacted his relationship with the local Jewish population. For he is known to have forced the Jews of Spain to convert under the threat of severe whipping.