The 1968 Chicago Democratic Convention

The sign over the archway leading to the International Amphitheatre welcomes delegates to the Democratic Convention, where anti-war candidate Eugene McCarthy and Vice-President Hubert Humphrey were to both seek their party's presidential nomination. Sitting president Lyndon Johnson had earlier that year announced his intention not to seek re-election Photograph: Corbis

Chicago mayor Richard J. Daley, hosting the Democrats in his city, on the convention floor Photograph: Wally McNamee/Corbis

The convention attracted famous names. Here actor Paul Newman and playwright Arthur Miller, both delegates from Connecticut, talk during the opening session Photograph: Corbis

Rival supporters of McCarthy and Humphrey wave placards and signs as the nomination session take place Photograph: AP

Humphrey wins. Mayor Daley and Illinois governor Sam Shapiro show their approval as the nominee greets the crowd Photograph: Corbis

Anti-war delegates protest at the decision to adopt the Johnson-Humphrey administration policy on the Vietnam war Photograph: Corbis

Reporting from the floor, CBS reporter Dan Rather (left) is shoved by security staff after he tried to find out why a Georgia delegate, holding a Georgia standard, walked to the rostrum and then out of the convention hall. Rather was then allegedly punched in the abdomen and knocked down. He said he was told to "get the hell out" Photograph: Corbis

Authors Allen Ginsberg and William S Burroughs (smoking) sit with French writer Jean Genet. They were taking part in the protest but also covering the convention for Vanity Fair Photograph: Getty

So-called yippies - militant hippie activists - march through downtown Chicago Photograph: Julian Wasser/Getty

The Yippies parading their alternative presidential candidate, Pigasus the pig Photograph: Julian Wasser/Getty

Hippies in Lincoln Park Photograph: Lee Balterman/Getty

Vietnam war protestors burn Draft cards Photograph: Chester Sheard/Corbis

Yippie demonstrators swarming a statue in Grant Park Photograph: Julian Wasser/Getty

Police clearing demonstrators from statue in Grant Park Photograph: Julian Wasser/Getty

A police dog caught on television cameras during a confrontation with protesters in park Photograph: Rex

One demonstrator prepares to throw back a tear gas grenade during a Yippie protest Photograph: Julian Wasser/Getty

A protester is led away by police Photograph: Lee Balterman/Getty

A crowd of protesters bombard a lone policeman Photograph: Julian Wasser/Getty

Police and demonstrators clash near the Conrad Hilton Hotel on Chicago's Michigan Avenue Photograph: Corbis

Illinois National Guardsmen seal off the Hilton Hotel convention headquarters from anti-war demonstrators Photograph: Gerald R. Brimacombe/Getty

National Guardsmen confront Yippies in front of the Hilton Hotel Photograph: Julian Wasser/Getty

Two unidentified protesters in Grant Park carry an anti-draft poster in front of National Guardsmen Photograph: Corbis

Police confront demonstrators Photograph: Julian Wasser/Getty

Police moving through a haze of tear gas in Lincoln Park while dispersing protesters Photograph: Art Shay/Getty

The Chicago Seven defendants, on trial the following year on charges of conspiracy to riot, hold a news conference in Chicago. From left, standing, are: Abbie Hoffman, John Froines, Lee Weiner, Dave Dellinger, Rennie Davis and Tom Hayden. Seated is defendant Jerry Rubin, with his girlfriend, Nancy Kurshan, who was not part of the trial Photograph: AP