It seems to be a habit of amateur historians to make parallels to their favorite wars. We won WWII, so the Republicans like that one. Vietnam reminds the Democrats when they were relevant, so they like that one. So, as America faces terrorism, we see facile parallels made out of hand. Either we face the danger of appeasement, or we face a quagmire. They're both wrong.
"Islamofascism" has no particular leader, and no expressed coherent doctrine, aside from the subjugation of all people on earth under dar al-Islam. There is no central figure to negotiate with, and no true negotiation. There will be no Munich when dealing with the Mullahs. In Islam, where every man is a caliph, there can be no negotiation. It would be as if every German in 1938 were Hitler.
It also isn't Vietnam. Vietnam was a civil war, funded by outside powers, intent on extending a sphere of influence into Southeast Asia. Again, there was an actual enemy that could be faced and defeated. The only parallel that might exist is one that the Left, assisted by the useful idiots in major media, are working diligently to bring about: the loss of American will to fight. North Vietnam was ready to surrender after the Tet offensive: their armies were destroyed, they failed to achieve any of their strategic, or tactical victories, and they were not in a position to continue their war. And then they watched Uncle Walter. Walter Cronkite, and many others, pronounced in stentorian tones that "The war in Vietnam is now unwinnable". That was enough to scotch the deal for the troops in the field. The assymetrical nature of the war is certainly similar, but again, we could negotiate with the enemy in question. In fact, we did. The communist government in Hanoi didn't seek the destruction of western culture (at least not directly), they sought to establish communism as the government for Southeast Asia as a whole.
The best template is Rome. Like Rome, we have extended the borders of our Empire to take in disparate cultures and countries, all with a sense of self-worth that is threatened by the presence of a superior. Like Rome, we are convinced of our own superiority. Unlike Rome, our Empire is commercial, and economic, not necessarily military. We conquer nations with Big Macs, Mickey Mouse, and Starbucks. Our military serves as an ancillary role to our economic interests. A casualtu of this is any individual identity of the culture we absorb and homogenize.
Rome did not seek to take over the Mediterranean Basin. At first their expansion was merely to gain hegemony over the Italian peninsula. Their status as sole superpower came as a result of the battle of Zama, and the fall of Carthage as a world power. Rome inherited Carthage's colonies, and their economic benefits, and along with victory came pride, giving the Romans an overarching sense of their superiority, and their right to determine the political future of the entire Mediterranean basin.
Post World War II saw a United States that didn't necessarily seek to be a sole superpower, but after 40 years, with the collapse of the Soviet Union, we now had an open field for commercial development. The homogenization of American culture had been developing since the end of the 1950s, and the rise of the interstate highway system. Local differences became less and less apparent, replaced by a few nationally known names, the aforementioned McDonalds, Disney, and Starbucks. With no great foreign threat, our commercial interests have been free to spread their influence, and continue the spread of uniform culture.
In the face of an imperial culture, seeking their subjugation, the barbarian cultures fought back. Pirates in the Mediterranean (there is an interesting editorial by Richard Harris from the NY Times:Pirates of the Mediterranean), Gauls in what is now France, Germans, Parthians, Numidians. Each of these cultures sought to free themselves of the yoke of the Romans, to preserve their own identity and freedom. Eventually they were crushed, or they learned to adapt, and to fight. As the Romans carried on their conquests, their armies had to be maintained as permanent garrisons, and their loyalty became more and more located in the place where they were, rather than with Rome. As the barbarians came in contact with the Romans, they lost their fear, and determined how to beat them. Teutoberg forest, the Parthians against Crassus, the Scots in Britain. Where once the threat of Rome's legions were enough, now open warfare was needed. It was a matter of time.
So too with America. Our empire extends around the globe, and it threatens the identity of other cultures. And one barbarian culture, that of Islam, is striking back, having lost its fear of the United States militarily. And our response has been anemic. Like Rome in its last days, we have abandoned our virtue in exchange for politics. Our armies are garrisoned around the world, we are becoming dependent on foreign cultures for our daily needs, and we no longer see self-sacrifice, honor, and dignity as necessary qualities. Mere wealth rules. We have become a nation of merchants and bankers, with our eyes on the bottom line. What sort of culture can we claim to be when denigration of the military is carried out as a matter of course in public debate?
It took four centuries for the fall of Rome to finally come about after the end of the Republic. Our end seems to be coming sooner. Our enemies are emboldened by our perceived weakness, and take advantage at our self-doubt. We just want to make sure that we can get the really good balsalmic vinegar.
Instead of debating which 20th century war this most resembles, and trying to suss out any particular importance, we should instead turn our eyes to the 1st century, and the beginning of the end of empire. What we see there are the seeds for our own downfall. The only response that seems prudent is to return to our original virtues: self-sufficiency, frugality, courage in the face of trials, and utter ruthlessness in dealing with our enemies. Half measures didn't work for Rome, and it won't work for us.