Background
When his father usurped the throne in 662, he left Benevento under Romuald and sent the deposed king Perctarit"s wife, Rodelinde, and son, Cunincpert, into exile at the Romuald"s court in Benevento.
Byzantine Emperor duke of Benevento
When his father usurped the throne in 662, he left Benevento under Romuald and sent the deposed king Perctarit"s wife, Rodelinde, and son, Cunincpert, into exile at the Romuald"s court in Benevento.
The Byzantines were then besieging Benevento and Romuald"s valiant defence of the city was failing, when Grimoald showed up and routed the Byzantine menace. Romuald then took Taranto and Brindisi, much limiting the Byzantine influence in the region. He received military aid from the Bulgar Alcek horde, which had resided in the south of the peninsula since the fall of Rome.
In return he gave them grazing rights in 667.