Gaius Duilius is a Classical Era Great Admiral in Civilization VI. His unit provides +5 
Combat Strength and +1 
Movement to Classical and Medieval era naval units within 2 tiles.
Gaius Duilius can be retired to form a Fleet out of a military naval unit.
Civilopedia entry[]
Since he was only a novus homo (simply meaning not one of the old Roman aristocracy), not much is known about the personal life of Gaius Duilius … other than he lived during the 3rd Century BC. But he did manage to somehow get himself elected consul in 260 BC, at the outbreak of the First Punic War. Junior to the patrician Gnaeus Scipio Asina operating in Sicily, Duilius was given the command of the Roman “rear” fleet, where it was expected he could stay out of trouble. But when Scipio Asina managed to get himself captured at the battle of the Lipari Islands, Gaius Duilius was suddenly in command of the whole fleet… or what remained of it.
Realizing that his forces lacked any skill whatsoever at naval warfare, and were facing a far superior (in every way) Carthaginian fleet, Duilius decided to fight under conditions as similar as possible to a land engagement, where the Romans were pretty good. Hence, he invented the corvus (a bridge equipped with a grappling iron). The following battle of Mylae was a stunning victory for Rome, the first Roman victory in a naval engagement against the Carthaginians; the smaller Roman fleet even captured a number of enemy ships, including the flagship. Duilius was rewarded with a triumphal march in Rome and a column (the columna rostrata) adorned with the “beaks” of Carthaginian warships in the Forum.
On a more practical note, in 258 Gaius Duilius was elected censor and in 231 BC he was empowered as a magistrate and given authority by the Senate to hold elections if he deemed the Republic in a state of emergency … the last historical record of him.
