Black Bloc protests in Chicago during NATO weekend.

Black Bloc protesters landed in Chicago to bring noise and destruction during the NATO summit. “What do we want? Dead cops!” the Black Bloc chanted.

Chicago has been geographically divided through street closures, and under a wave of mishaps and mayhem that include flu-like symptoms, computer hacks, protests, arrests, and now this — Black Bloc Anarchists who faced off with cops on Sunday. It happened in Grant Park, the park where President Barack Obama learned of his win in 2008.

Shortly after war veterans peacefully returned their medals in a show of protest against the war, a group of 100 “Black Bloc” anarchists surged forward toward Chicago cops on live television.

Black Bloc is not a group, it is a tactic according to DePaul University professor Tom Mockaitis: “It developed in Germany in the 1930′s as a response to what peaceful protesters believed [were] overly aggressive police tactics and arrests.”

What makes the Black Bloc so problematic for police, is their tactic after engaging in violence. They wear black clothes to hide their identity and to ditch the black clothing, quickly melt back into that crowd, ditch be unrecognizable…and impossible to arrest.

The Black Bloc group cried: What do we want? Dead cops!” as they attempted to breach the Chicago cops in riot gear.

Arrests were made and nightsticks were used in a display of ugliness that city officials and NATO organizers worked feverishly to avoid.

The clash left several bloody protesters, at least three injured cops and a stabbed onlooker, just blocks away from Chicago’s rolling out offices on Michigan.

Additionally, Chicago police arrested seven men and women, all wearing black, at about 1 p.m. in Grant Park near Michigan Avenue and Harrison Street on Sunday.

A police sergeant said the Black Bloc protesters had in their possession: “About 20 rocks, cans of spray paint, pry bars, urine-filled bottles and other dangerous weapons.”