Alfonso III of Asturias repopulated the strategically important city Leon and established it as his capital. King Alfonso began a series of campaigns to establish control over all the lands north of the Douro river. He reorganized his territories into the major duchies (Galicia and Portugal) and major counties (Saldaña and Castile), and fortified the borders with many castles. At his death in 910 the shift in regional power was completed as the kingdom became the Kingdom of Leon. From this power base, his heir Ordoño II was able to organize attacks against Toledo and even Seville.