And it was against this backdrop that a new idea began to win adherents.
"Stopping the war in Vietnam was important to me and we wanted to ... we were peace activists," explains author and photographer Rex Weyler. "But we knew that there was something else brewing and this was the environmental movement, this was ecology; we kept saying ecology is the next big thing."
But the Cold War was raging and a nuclear arms race was on.
In 1969, the US announced that it would be carrying out an underground test: the detonation of a one megatonne bomb on the island of Amchitka in Alaska - 7,000km northwest of Vancouver.
Georges Payrastre, who was living in Vancouver at the time, says: "I was astounded that a country like the United States could even think of carrying out nuclear tests at such close range ... It really seemed like it was in our backyard."
In October 1969, thousands of activists protested against the Amchitka nuclear tests at the border between British Columbia and Washington state. But the Americans went ahead - detonating the bomb and announcing plans for a second nuclear weapon test in a year.
In protest at this, a Quebecer and an American Quaker couple formed the Don't Make a Wave Committee - the precursor of Greenpeace.
Inspired by the pacifist Quaker tradition, the committee proposed sending a ship into the American nuclear testing zone in Alaska. To finance this first mission, co-founder Irving Stowe suggested holding a benefit concert.
Held on October 16, 1970, the concert featured Joni Mitchell, James Taylor, Phil Ochs and the group Chilliwack. It raised $17,000 - enough to finance the organisation's very first mission.
On September 15, 1971, Captain John Cormack and 12 Greenpeace activists set sail for Amchitka during the dangerous stormy season.
Two Greenpeace members, journalists Bob Hunter and Ben Metcalfe, filed reports from the ship to newspapers and radio stations.
Fifteen days after its departure, the ship was stopped by the US coast guard and warned not to go any further.
Although the mission did not prevent the explosion, it was widely reported in the press and drew public attention to nuclear testing. It was the group's first campaign and its first media victory.
Now it has offices in 40 countries around the world, close to three million members and controls a budget of $150m.
This film tells the story of the group's evolution from hippies to lobbyists.