Four

Tin soldiers and Nixon's coming
We're finally on our own
This summer I hear the drumming
Four dead in Ohio. 

Neil Young's cri de couer about May 4 1970 on the radio, while protests continue in Hong Kong and with thoughts of Awakenings past still resonating, became a reminder that not all movements work out as intended.  Even if a protest doesn't succeed, though - even when it fails spectacularly - that doesn't mean it didn't make a difference,  that it wasn't important. 

Bryan lost to McKinley, then tried and lost again. Theodore Roosevelt, though, would soon after become known as a trust buster, taking on moneyed interests in a way that probably exceeded any potential effects of the coinage standard.  While the four students killed at Kent State ended an age when student protest meant something - and might be considered the point at which Hunter S. Thompson's "wave" began to roll back - the U.S involvement in Vietnam would stop soon after, and Nixon would resign 18 months into his second term. These are successes for their movements. That there were well-publicized failures along the way doesn't diminish them. 

Few would be paying attention to the minutiae of Chinese election law or the unusual history of capitalism in Hong Kong without the protests there now.  Indeed, while the Chinese government officially proclaims the necessity of the crackdown in Tiananmen Square in 1989, there seems to be some recognition that it was a major failure on their diplomatic front. It may turn out that the resolution in Hong Kong - however it might turn out - will owe some debt to that. 

Then again, based on reports of pro-government counter-protesters, it might follow a template that the Russians have found successful. Even that will say something about the next fifty years, there.