After consolidating his rule over the western provinces, Severus waged another brief, more successful war in the east against the Parthian Empire, sacking their capital Ctesiphon in 197 and expanding the eastern frontier to the Tigris. He then enlarged and fortified the "Limes Arabicus" in Arabia Petraea. In 202, he campaigned in Africa and Mauretania against the Garamantes, capturing their capital Garama and expanding the "Limes Tripolitanus" along the southern desert frontier of the empire. He proclaimed as "augusti" (co-emperors) his elder son Caracalla in 198 and his younger son Geta in 209, both born of his second wife Julia Domna.