 In 899, Atenulf I defeated Radelchis II and conquered Benevento.He declared Capua and Benevento inseparable and introduced the principle of co-rule, whereby sons would be associated with their fathers and brothers with each other, a principle soon borrowed by Salerno.Atenulf associated his son, Landulf, as co-prince and built up alliances with the local Greek states, like Naples and Gaeta, which alliances were continued under his successor.