It started as a rally, turned into a party and briefly became an altercation. The party resumed and then it got very ugly.
A roving band of 400 demonstrators started an "anti-car" demonstration at the GPO on O'Connell Street in Dublin. As the group moved on to Burgh Quay, it blocked off the end of Butt Bridge.
Gardaí moved in and cut away the blockade but allowed the rally to continue.
The initial disruption started when participants in a so-called "Reclaim the Streets" rally pushed a car out on to Burgh Quay from a laneway, smashed the window and threw a smoke bomb into it. Scuffles broke out as gardaí attempted to move the car back on to Corn Exchange Lane and in the brief altercation, a number of people were arrested.
Participants claimed the car was owned by one of the demonstrators and it was a "symbolic anti-car gesture" to reclaim the streets for pedestrians, cyclists and motor cyclists.
Earlier some of the 400 people who took part in the rally taunted gardaí monitoring the parade. The rally was at times like a festival event with alcohol, musicians, and people in fancy dress costumes, including one man in little more than a leather thong and braces.
However, a large number of people moved through Temple Bar and on to Dame Street and disrupted traffic completely for about 10 minutes. The initial festival mood turned ugly as protesters clashed with gardaí, a number of whom used truncheons to move demonstrators off the streets.
One onlooker, Mr Kevin Quinn from Dublin, said he had been in "Paris in 1968 and I never saw such savagery. It's like a dictatorship." He added that there was a "diplomatic" way to handle these protests.
A Garda spokesman said he could not comment on claims of brutality until investigations were complete as a number of people had been charged and their cases could not be prejudiced.
After most of the protesters dispersed, some continued on to the Civic Offices where they were surrounded by gardaí.
Earlier at Burgh Quay, Insp John Keenan of Store Street described the event as a globalisation resistance protest.
Ms Lorraine McLoughlin, a student at Dún Laoghaire Institute said she attended a "party" and said: "Just because people are disrupting traffic, having police beat you on the head is not on."
