This served to avert a civil war in which the intervention of the Emperor Frederick II, who was not on good terms with Boniface, could have been expected.
He proposed to marry Margaret, daughter of Amadeus IV of Savoy, but her grandfather Thomas I refused to grant the marriage while she was still very young.
The two were wed in December 1235 at Chivasso,[2] his capital, and Margaret became the mother of the future William VII[2] and of Alessia (also called Alessina, Adelaide, Adelheid).
Amadeus appears to have concluded an agreement with Boniface whereby the latter would succeed to his Alpine Piedmontese lands if the Savoyard died without heirs.
Boniface's main sights, however, were not on the Piedmont but on nearby Alessandria: from 1227, when he strengthened an alliance with Asti, he continued until his death to fight the Alessandrini.
He escorted the Emperor on his Italian journeys and, in 1239, Frederick invested him with Thessalonica, which had originally been conquered by his grandfather in the aftermath of the Fourth Crusade.
Thenceforward distracted by the fight for the southern Piedmont, Boniface dedicated more energy to internal affairs than to warmaking.