In 1469, Brittany sent a ship to the new world which found to Caroline too, but the stronger Dutch didn't allow them to make landfall. However, in 1486 France sent the first ships to Atlantis, under a captain Coulon (of the infamous pirate family), making claim in the area of Caroline, where they founded Charlesbourg at the site of OTL Charleston.
Toward the end of the anti-French War, Friedrich von Hohenzollern, a German in the service of the governor of Italia Nuova, made "The Wild Ride" 1692: He fought his way through Caroline with his cavalry troops, finally linking up with the Spaniards in Florida. In the peace of Amsterdam of 1694, Caroline shrank as the colony of Virginia went back to Spain.
During the second French Civil War, 1765 the governors of Caroline (and Nouvelle France, Algeria, and Louisiane) declared independence - until France would have a king again. Lacking a navy (because the mostly noble captains didn't want to fight for a republic and thus deserted), France couldn't take them back. But in 1771, as one of his first deeds, king Gioacchino of Italy sent troops to Atlantis and attacked Caroline, south of Italia Nuova, which was conquered and added to Italia Nuova until 1773.