Hundreds of demonstrators descended onto Manhattan's Financial District this past weekend, intent on protesting U.S. banking institutions and interrupting the flow of Wall Street.  The social media-fueled protest had called for 20,000 hearty souls to "flood into lower Manhattan, set up beds, kitchens, [and] peaceful barricades, and occupy Wall Street for a few months.  But by Sunday, fewer than 500 had assembled, and that number dwindled to 200 hearty souls by Monday morning. Protest Organizers. The demonstration is an outgrowth of an article titled #OccupyWallStreet on Adbusters, a nonprofit anti-consumer organization that runs a magazine.  Groups such as NYC General Assembly and U.S. Day of Rage spent months using social-media sites like Twitter to draw as many 20,000 people to Wall Street. Blocked from Wall Street by police, the protesters made Zuccotti Park and Liberty Plaza their home bases, for keeping food, sleeping bags, tents, and for having "General Assembly" meetings about how to present their diverse views to the public. Protesters Meet Police Resistance. A law-enforcement official speaking on condition of anonymity said the demonstration has remained largely peaceful.  Two men were arrested Saturday afternoon for disorderly conduct;  police said they were loitering while wearing bandanas over their faces and yelling about corporate corruption. The official said police were prepared for the protests, bulking up manpower and closing off streets in advance.  Over the weekend, police blocked off entrances to Wall Street at William Street and Broadway to the east and west, the corner of Pine and Nassau streets to the north and Broad and Beaver streets to the south.  "No one who doesn't have legitimate business or live on Wall Street is allowed past barricades," the official said.  And while the group had no permit to demonstrate in the area, the city allowed them to peacefully demonstrate. Portraits of Peaceful Protesters, As Captured by Bloomberg Photographer Amy Arbus.