Hi! New member here, so be gentle please. I was surprised to find out that there's such a vibrant AH community on the web (I'm not sure why, there's a community of everything on the web). I'm not well-versed in AH, and it's not my intention to make a timeline. I'm actually writing a fantasy novel, but imho, the best fantasy is based on reality, so figuring out the what why and how of a theoretical Roman expansion into the New World will be immensely helpful in putting together a believable plot. I am an anthropologist, so that's my background.
Let me start by saying that I've read all the similar threads on the board. I didn't want to necro them, as some of them were actually pretty flamey in places, although they did have a wealth of useful info. I agree with many posters that getting the Romans to even attempt the trans-atlantic voyage is the trick. There's no motivation for anyone to sail into a seemingly endless unknown ocean.
So, the simplest way for us to round up that motivation for Romans is to have the Americas, or at least the Caribbean Islands, as having already been discovered. To this end, I hope to employ Rome's staunchest opponents, those baby-eating Carthaginians. And of course, any discovery of the Americas presupposes knowledge of currents and trade winds, specifically the Volta do Mar. And the most convenient jumping-on point for that oceanic circuit is Macaronesia, specifically Cape Verde.
The Carthaginians were familiar with at least some of those islands. The voyages of Hanno the Navigator were some of the first mention of the Canary Islands. In the fifth century, he and a force of 60 ships sailed down the African coast perhaps as far as Senegal with a mission to found Carthaginian colonies and thereby exploit the gold-rich West African coast. Some centuries before this (I've heard estimates as far back as the 12th cent.), Herodotus reports that an expedition of Phoenician ships circumnavigated Africa at the behest of the pharoah Necho of Egypt. Phoenicians are, of course, the forefathers of the Punic population of Carthage. They, too, most likely encountered the Canary Islands and perhaps others on their circuitous route.
After Hanno, the next visitors to the island are a Roman expedition led by Juba II of Mauretania on behalf of Augustus around 40 BC, many years after the conclusion of the Punic Wars. He found stone ruins there, evidence of a skillful civilization. He also found natives, whom he deemed too primitive to have carried out such building projects. The natives reportedly had no navigational skills or knowledge.
Let's set our PoD way back there with that first group of Phoenicians on a quest for the pharoah. Say they did make shore on the Canaries, where they discovered an abundance of some shellfish or lichen that produced an especially fine dye. And as the Phoenicians were wont to do, they left behind several hundred men with supplies and formed a small enclave there to exploit the resource. The rest of the expedition completed the journey, as in OTL, but the small enclave left on the lsland is largely forgotten. Until a couple centuries later, when who should arrive but Hanno, finding not an uninhabited series of islands, but a thriving colony, spread out already to inhabit several adjacent islands, and awash in expensive dyes. They've also begun to adapt Phoenician ship designs to better deal with island hopping in the Atlantic. Not only that, but they speak a language that's mutually intelligible to Hanno's own, and perhaps worship the same gods.
Realizing that these colonists are brothers, Hanno supplies them with goods from Carthage, and begins a mutually beneficial trade partnership. The colony now begins to expand at a more rapid pace, and eventually spreads throughout not only the Canaries, but to greater Macaronesia, including Cape Verde. Now, with a few centuries of island hopping under their belts, the Phoenicians are starting to understand the trade winds, and they've almost certainly made greater innovations in ship design and navigation. Now, the Punic people, the most far-ranging sailors of the Mediterranean, are prepared for their greatest journey yet. THIS PART STILL NEEDS A MOTIVATOR, I know. There needs to be some force driving them west, or at least telling them that there is a west to sail to. Regardless, the Phoenicians do make the journey and continue their pattern of setting up trade enclaves in the Caribbean and possibly Mexico or Central America. And little by little, New World commodities start to make their way into the Mediterranean by way of the Phoenician traders.
Now, if not too many butterflies are stirring already at this time, the Romans will still inherit most of Carthage's colonies at the end of the Punic Wars. When Juba II visits the islands in 40 BC, he'll find not a bunch of ruined buildings and backwards natives, but an advanced civilization with an established trans-Atlantic trade.
I'll pause here. Now, posters in some of the other threads seemed to believe that this kind of long-distance high-risk activity was not characteristic of the Romans. But I believe that the Romans enjoyed exotic luxury goods every bit as much, if not more, than Western Europe at the time of contact. Pliny, in fact, expressed his perturbance at so much gold from Rome's coffers being shipped off to the Orient for exotic fineries. Once the Romans got a taste for chiles, and tobacco, and chocolate, and all the other goods that the West had to offer (let's not forget tomatoes- the Italians really seemed to take a liking to them), the equestrians would be scrambling over each other to get there.
We can talk about the technology too. The Romans, contrary to popular belief, had both lateen sails and rudders (just not the stern-mounted kind). The Carthaginians were much more accomplished sailors, and would have had ample time to improve in the Atlantic in this scenario. I realize that the compass wouldn't be invented for a long time. There's that. But how much of a leap is it? What do you need to know before you invent a compass? Or an astrolabe? I'm sure there was some version of Jacob's staff back then. I'm not an expert on navigation, but it seems that these innovations were borne of necessity, when a great enough motivation presented itself. Possibly, if that motivation had presented itself sooner, the innovation would have come sooner as well. Much sooner, in this case.
I'm sure I've forgotten some stuff, but there's plenty of time to hash it out. So try and poke holes in it, and I'll plug them with fingers. Help me figure out what could possibly turn the attention of the colonists to the west (and please don't say freak storm/shipwreck). Also, how did the Portugese and Spanish discover the Volta do Mar in OTL? In advance, I appreciate all your thoughtful responses (you know, the responses where you don't call me a retard). Thanks!