On this day in 1968, hundreds of demonstrators braved searing heat and KGB threats of arrest (or even execution) to hold an anti-nuclear and anti-Brezhnev rally in Moscow's Red Square.

The demonstration became a riot when Soviet security forces attacked the protestors, killing twenty and provoking the rest to lash out in an orgy of violent unrest the likes of which Moscow hadn't seen since the 1917 October Revolution.