We retreated after taking massive losses and accomplishing none of our strategic objectives, unless you consider sending a generation of youth, poisoning the land for generations, and committing countless atrocities to be the real objectives, rather than the stated goal of preventing Vietnam, a country that is still communist to this day, from becoming communist?
Unrelated, but the other day, someone cornered me in an alley with a gun and demanded I hand over my wallet - but I didn't lose to them! I simply put my hands up and abandoned my wallet, very different.