I know this is evidence of ageing boomerdom, but the Vietnamese victory over the US at the end of April 1975 (and some allies, such as Australia), after their victory over France in 1954, was a defining moment for many of us who spent much of our youth marching and protesting against this protracted war with its enormous use of chemical weapons as well as conventional bombs against a much smaller and poorer country; the Vietnamese winning with much cruder weaponry (but with great military strategists), as they had won over the French two decades earlier.
It was an inspiration for many people and peoples around the world. Yes, a civil war is never "polite" and there were many people who had supported the US-tied regime, and others who had different reasons not to support the new government who fled the country. But the Vietnamese achievement had an impact on a whole generation on all continents and made many of us anticapitalists who refused societies based on exploitation and oppression, and imperialism abroad. Yes, many of these young leftists sold out or gave up (we can name some infamous cases) but there are people, including the founder of rabble, whose commitment to the struggle has been a lifelong one.