Hence it came to be used for 'heaven'; as in the present passage.
II.

Jupiter is referring to the invasion of Italy by Hannibal in 218 B.C.
IV.

Diomedes, the son of Tydeus from Aetolia, is said to have settled, after the Trojan war, in Apulia, where he founded the city of Arpi.
The Latins, it will be remembered, had asked him to help them against the Trojans.

See Book VIII.

stanza ii.