Following the war in Vietnam, our Army was figuratively decimated. It took a long time to reorient the Army and rebuild its ability to fight. Compare that experience and outcome with the Army that came out of Iraq and Afghanistan.
Given that many on the left insist we lost both the Iraq War and the Afghanistan War (after demoting it from "good war" status after the Iraq War wound down), why didn't our Army and Marines suffer from those defeats after the war? Why did they continue to be effective with good morale and training? Shouldn't they have been broken as they were after our justly deserved (remember, from the left's point of view) defeat in Vietnam?
Of course, victory versus defeat is a difficult judgment. Even in Vietnam we defeated the North Vietnamese and left South Vietnam intact, if battered and without full control of their territory. Reliant on our support and facing a major conventional threat from Hanoi, South Vietnam fell to a North Vietnamese invasion a little over two years after we left.
In Iraq, a little over two years after we left, jihadis took over large parts of Anbar and then overran large parts of the north, including Mosul. Yet Iraq did not fall. And we returned to help Iraq hold the line, and (we say) eventually reclaim their territory.
And in Afghanistan, we are nearly out with the intent of having all our troops out in two years, despite the continued presence of enemy forces in (mostly) the south and east. The outcome remains in doubt, at least, with reasons to believe either outcome could happen.
But regardless, our ground forces--especially the Army--were broken after leaving Vietnam--and it didn't need to wait until the fall of Saigon to break. Not broken after Iraq--even after the ISIL offensives. And not broken after largely leaving Afghanistan--and who thinks it would break even if the Taliban regain control in two years?
The key is that in Iraq and Afghanistan, we withdrew units. They retained cohesion and as units they know they did their jobs and did their jobs well. And it doesn't matter if you judge those wars lost or won.
In Vietnam, as I've noted before, we withdrew individuals rather than units and left an increasingly smaller mob of individuals behind to hold the line until we pulled them all out.
There are other differences, too. We had the draft back then and have volunteers now. The casualties in Vietnam were nearly an order of magnitude greater than the combined casualties in Iraq and Afghanistan. And public support for the troops was sustained in the latter wars even as support for keeping the troops fighting declined, in contrast to the hate for the troops that existed during Vietnam in some circles.
(Indeed, I always assume that support for the draft today on the left is motivated by the desire to recreate that hate to undermine our ability to fight wars.)
But I think that unit cohesion is the key to maintaining an effective military even in defeat. Remember, war from the foxhole gives you a different perspective than looking at the large-scale maps and pondering the grand sweep of the war.
If you are in the foxhole, you judge success by what is going on near you and not the bigger picture.
I've noted before that my limited experience in the military only gave me hints about what those who go to war experience. But I did get hints. And one of them was this difference between perspectives.
Such as the night my unit was going into the field for a training exercise to test our knowledge on the new equipment we had been trained on. That night, word of the August 1991 coup in Moscow came across the radio in our barracks.
That was of intense interest to me. Yet over the next four days, during which I never had more than a five-hour stretch of sleep, my focus was on using our new equipment, including a teletype machine we'd soon ditch for a field fax machine, rather than following the coup that was taking place in a nuclear-armed state recently defeated in the Cold War.
So don't let anything interfere with our unit cohesion. Don't take shortcuts to save money, even during sequestration, because we want an army in our barracks and not an armed mob.