[Ridwan]

Originally Posted by ChainLegacy

The thing is, at that point Rome was just a backwater civilization with little to call an empire. Were they lost to history, their heavily Mediterranean cultural inheritance from the Greeks would never filter into Western Europe at the rate it did.

If the Gauls conquered Rome, they would not then transfer Greek knowledge as the Romans had, for this was prior to Rome exerting any influence over Western Europe. Of course, Greek merchants were already having an influence on the Celtic peoples as far back as the Hallstat cultures, but the influence had more to do with status symbol items like wine and amphorae. Material culture, values, philosophy, and of course religion were all heavily altered in Western Europe by the Roman Empire. In their absence, there would be no Christian Europe, far less philosophical ideology from the Greek masters (individualism being a big one), and probably a number of other intangible cultural qualities would be different. Remember, while the Celts and Germanic tribes were related to the Romans, they were in many ways completely separate cultures, cut off for thousands of years.

Your assertion that military differences would be the main discernible change I would have to disagree with. For a parallel, look at Japanese culture. Since the Meiji Restoration, Japan has opened its culture to the West and actively promoted cultural diffusion so as to better compete. In the span of 150 years they have made a massive transformation and while their culture is still quite different from Western cultures, the similarities are striking for such a short period of change. One can see how, in a Roman-dominated Europe, the Celts would be forced to adopt Roman ways to survive, much like the Japanese during the Meiji era. Except in the Celts' case they had hundreds of years to be assimilated and lose their culture. Without a Roman empire to unite and homogenize these disparate groups around Western Europe, the cultural traditions of the West may have been completely different.

But yes, militarily things would be completely different. Which would tie in to different ethnic lines along Europe. Germanic invasions, as well as Latin settlement, could have happened at much different rates. The Celts, who were more or less absorbed by all the latecomers into Western Europe, might have continued to exist as a cultural group.

Originally Posted by Kokukirin

If Gauls were to conquer Rome, their closer proximity to Greece would almost certainly increase trade and possibly warfare between them. In most cases of history, the cultural centre of a region always spread their culture and influence the people coming into contact. Usually the less-developed civilizations would borrow heavily from it, bringing in its philosophies, cultures, literatures, and religion. It happened to civilizations around China. It happened to Romans and Persians around actual Greece. Almost inevitably the Gauls would be heavily influenced by the Greeks in the imaginary scenario as well.

I didn't make it clear in my last post. My main point was that whoever conquered Italy at the time would likely be unable to replicate Roman's military success. Such dominance in military might for extended period of time is very rare. And consequently, the events that required the Roman military successes could not be counted on to happen. Such events include many that you pointed out: the assimilation of Celtic and Germanic tribes into a common culture, the establishment of Christendom across Europe. So yes, I agree with your assessment here.

I actually had done this in my previous post, but there is a timeline that you guys will might find it interesting. It's The Weighted Scales: The World of an Aborted Rome, a scenario authored by a friend. It's a world where Rome got destroyed by the invading Gallic tribe of the Senones who ravaged central Italy and put away any hope for the natives to build any great empire in the future.