When did Roman Gods....become the Greek gods

It is known that the early Roman gods were rather different from their Greek counterparts. When did them Pantheons merge so to speak. Venus was originally a goddess of vegetation and vineyards, but she later became subsumed by Aphrodite.

This was more than just the Roman (and to a lesser extent Greek) tendency to combine identify foreign deities with their own, the foreign deities became the local deities.
When did this happen and when was the process complete.

The Greeks had been establishing colonies in Sicily and the Italian mainland since the 8th century BC. Rome conquered Sicily in 264 BC and the Greek mainland in 146 BC. I would imagine the exposure to Greek culture was soon complete:

Wiki: "The Greek peninsula came under Roman rule in 146 BC, Macedonia being a Roman province, while southern Greece came under the surveillance of Macedonia’s praefect. However, some Greek poleis managed to maintain a partial independence and avoid taxation. The Aegean islands were added to this territory in 133 BC. Athens and other Greek cities revolted in 88 BC, and the peninsula was crushed by the Roman general Sulla. The Roman civil wars devastated the land even further, until Augustus organized the peninsula as the province of Achaea in 27 BC.

Greece was the key eastern province of the Roman Empire, as the Roman culture had long been in fact Greco-Roman. The Greek language served as a lingua franca in the East and in Italy, and many Greek intellectuals such as Galen would perform most of their work in Rome.

Several emperors contributed new buildings to Greek cities, especially in the Athenian agora, where the Agrippeia of Marcus Vipsanius Agrippa, the Library of Titus Flavius Pantaenus, and the Tower of the Winds, among others, were built. Life in Greece continued under the Roman Empire much the same as it had previously. Roman culture was highly influenced by the Greeks; as Horace said, Graecia capta ferum victorem cepit. (Translation: Captive Greece captured her rude conqueror.) The epics of Homer inspired the Aeneid of Virgil, and authors such as Seneca the younger wrote using Greek styles. The Roman nobles who regarded the Greeks as backwards and petty, were the main political opponents of Roman heroes such as Scipio Africanus, who tended to study philosophy and regard Greek culture and science as an example to be followed. Similarly, most Roman emperors maintained an admiration for things Greek in nature. The Roman Emperor Nero visited Greece in 66 AD, and performed at the Ancient Olympic Games, despite the rules against non-Greek participation. He was, of course, honoured with a victory in every contest, and in 67 AD he proclaimed the freedom of the Greeks at the Isthmian Games in Corinth, just as Flamininus had over 200 years previously. Hadrian was also particularly fond of the Greeks; before he became emperor he served as an eponymous archon of Athens. He also built his Arch of Hadrian there."

True, but that with respect does not answer my question. The Roman pantheon was more or less Greek well before the conquest of Greece,latest by the second Punic War, if not before.

The simplistic equation of the Greek and Roman gods is a bit exaggerated. Neither system was ever static, and neither was uniform. The Romans assumed the Greeks were worshipping the same gods as they did, only under their Greek names. Occasionally that was even true: Zeus really is the same as Juppiter, etymologically at least. With the tremendous Roman admiration for Greek philosophy and culture, the Roman view of their own system gradually took on more and more Greek content. Some of this “Greek” stuff, though, comes from Ovid, and we have no idea whether or not it was current in ancient Greece, and some distinctively Roman elements remained (e.g. the foundation myths), often more visible on the level of festival than in literary verions of myths. In other words, I question your OP.

That said, we know the Etruscans were already depicting specifically Greek myths in their art, so the diffusion of Greek myths beyond the Greeks is quite old indeed.

By the way, where did you get the idea that Venus was a vegetation goddess?

Right here

As for the rest, thanks. However I think my point stands. The Romans certainly kept some things unique in their system, Mars is far more of a heroic and admirable god than the slightly ridiculous thing Ares is and Venus is also a goddess of military victory; which IIRC Aphrodite was not, but my point remains. Romans tended to see their own gods in others worship, but in the case of the Greeks it was a whole scale borrowing. Admittedly the Romans began writing their history mostly after the second Punic War so it would be perhaps difficult to compare, but there is evidence that at least earlier the Roman Pantheon was quite different.

Actually, I understood this to be a pattern of the Roman Empire. When they conquered more territory, they often ruled it by taking over the top level of the previous leadership. They installed a Roman as Governor or Prefect, but they mostly ruled through the existing chain of command. And as part of merging them into the Roman world, they would try to find similarities between the local gods and Roman ones, and then proclaim that these were the same god with different names.

Part of the cultural conquest of the Empire. The Romans were largely content to rule conquered lands and collect taxes – they seldom did the ‘slaughter all the people & animals, burn every building & field’ that some other conquerors did.

Tell that to the Carthage. Also, they razed entire villages of tribes in Gaul that held out against Caesar and cut off the hands of everyman that fought against Rome. As far as I know they didn’t try to equate Gallic or British druidic gods with Roman gods and very little merging happened between Egyptian and Roman gods as well.

They most certainly did: check out Caesar’s Gallic War, book six, where he describes a half-dozen Gaulish gods with the Latin names, and there is a mountain of epigraphic evidence of gods whose Gaulish name is written alongside the Roman equivalent, e.g. Apollo Grannus. I don’t know much about their views on Egypt but I would be surprised if they hadn’t done the same. The approach wasn’t uniform, as some Romans adopted the worship of Epona (Gaulish) or Isis (Egyptian) rather than a Roman equivalent.

They thought this about everyone’s gods. I just was recently Wikipedia hopping, and discovered that the Jewish god was assumed to be Caelus, primordial god of the sky (similar to, but probably not derived from, Uranus).

(If you care, I was wondering why the planet Uranus alone uses a Greek name.)

Both were derived from the Indo-European pantheon, so there were bound to be similarities. But as you note, all religions change over time and so we’re probably looking at two cultures who derived from a common culture about 2-3K years prior. I could be off on those dates, but something like that.

The Forum Boarium in Rome provides good material regarding these issues. Its altar to Hercules is from 5th or 6th century BC, just when Rome is beginning to enter the historical record.

The cult site is founded where Hercules defeated Cacus, an event essential to Roman foundation myths. Subsequently Hercules-as-conqueror-of-Cacus becomes a standard element for assertions of Roman identity in political discourse. Indeed Romans shaped the Hercules story as much as they are shaped by it. Yet there is no question that the Hercules of the Forum Boarium is very Greek. The forum was very oriented towards foreign trade and a 2nd century BC temple to Hercules in it is done in full-blooded Greek style.

Rome is deeply influenced by the Greeks from the get go. Its culture and religions are always distinctively Roman, but nevertheless Greek influence is never absent even at the beginning of the historical period. Greek influence must have grown a great deal with the Greek colonization of southern Italy in the 8th and 7th centuries BC, and it was probably already present before then.

If I may be permitted a slight digression, I am often amazed at the tolerance the ancients had for lack of continuity in their tales. Where were the nerds who in our own time pick apart incompatible manifestations of costumed super-heroes? Suddenly we’re to believe that Aphrodite, cum Venus, is a paragon of civic virtue? Surely we’re only being set up for a Magneto-like betrayal. Hephaestus, whom we were introduced to as a clever but hideous cripple is now Vulcanus, super-stud? At least put out a limited series to explain this transition. And can we get a god of agriculture that doesn’t get transmogrified into a god of war to appease the newbs with the backwards baseball caps, or pilea as they called them in those days?

Religion has been going downhill ever since the death of Tarquinius, and don’t even get me started on Constantius.

Don’t you remember, after “Crisis on Infinite Mt Olympi”, there was a total reboot.

They killed them. Things were simpler back then.