The son of Publius Servilius Geminus, Gnaeus Geminus was elected as consul in early 217 BC. By March of that year, Geminus began directing military operations against the Carthaginian General Hannibal around Ariminum. Following the death of the consul Gaius Flaminius at the Battle of Lake Trasimene (Trasimeno) in April (as well as the rise to power of dictator Fabius Maximus the following month), Geminus assumed command of the Roman fleet overseeing coastal defense and battles against Sardinia, Corsica and the North African coast.