The counter-culture years of the mid to late 1960s saw social change like no other period in modern history. It's only with the benefit of 50 years of hindsight that we can now understand the extent to which these events all bore the fingerprints of the military-intelligence communities, and all set to an acid-fuelled soundtrack of tripped-out rock. On the basis that music speaks louder than words, here's the fascinating story of those five era-defining years as told by the music, with a few audio snippets from some key events along the way.