What? You don't think Tet was a military victory for the US and South Vietnam?
Tsk tsk tsk, such imprecision, such a fallacy of ambiguity. Let's take a look at what you originally wrote:
... Tet in Vietnam. Turn a great victory into a defeat.
So you were initially claiming it was a "great victory", now you've suddenly changed your tune, according to you it's now only a "military victory" and no longer a great one.
Let's look at what happened with Tet; just before Tet, generals and politicians were claiming that victory had already been won in Vietnam. They claimed this in a big way (sound familiar?). Then ........... Tet happened. And all of a sudden all the previous claims were shown to be false.
Let's look at what happened after Tet; 2 years after, North Vietnam had made good most losses, and also turned it all from largely a South Vietnamese insurgency into a North Vietnamese effort. IOW, the USA and the ARVN had managed to politically change the whole thing without realising it; and that change had consequences. Up till round 1962, it's quite possible that the USA could have won a political victory of sorts in Vietnam; after round 1962 it became ever more impossible, and Tet simply raised the stakes very high indeed -- and while most of the VietCong were wiped out, the North Vietnamese were still able to make up for the losses, and less than a decade later had won the whole shebang.
I do wish you would study some history, BAC.
Hate to tell you but it was. Very clearly. Even the North Vietnamese commander who eventually accepted the surrender of the South is on record saying it was
Which of course completely fails to explain why Saigon is now Ho-Chi-Minh City . Back to your fallacy of ambiguity ......
Then they realized that the US had no WILL
Yeah, I guess the USA and Australia could have sacrificed double as many casualties in pursuit of nebulous goals and in support of an utterly corrupt regime totally out of touch with its own people just to satisfy armchair warriors chuntering on about Will (so very Wagnerian! So very ....

), but I guess the more responsible of politicians could see there was bugger all point to the USA or Australia being in Vietnam in the first place, and all very ironic in view of the fact that the USA initially supported de-colonialisation after WW2 (and gained much respect worldwide for doing so, and arguably prevented many worse conflicts from happening by doing so; but .... well, just kinda .... buggered up in Vietnam).
Thank Nixon.

And don't bother, I know what you would say next.