Steve Venus, one of the protesters who built the structure, said earlier this week that his intention was to make it as difficult as possible for police to remove it when the eviction began.
Rumors about exactly when that would happen gained strength and credence Tuesday, but by midnight, only a dozen protesters had gathered, anticipating a confrontation with police.
Shortly after midnight, when Twitter reports began warning that police were gathering and phalanxes of patrol cars were closing in on the plaza, a man ran through the encampment, frantically crying out, "Cops! Occupy Philly!! Wake up!! Everybody up! Up and at 'em! Let's GO!"
The warnings failed to rouse many of the people sleeping in tents. But several dozen other Occupy activists were gathered on the steps facing west, preparing to meet the police with peaceful, but firm resistance.
"I have mixed feelings," said Julia Alford-Fowler, a 33-year-old graduate student at Temple University. Alford-Fowler has been working with the Occupy movement since it started in October and volunteers for the legal collective. She was home in Port Richmond, getting ready for bed, when she saw tweets about the imminent eviction, so she got dressed and came to the plaza.
While she regrets the city's decision to force Occupy to move, she said, "I don't want to stand in the way of jobs."
She wishes that the city would grant a permit to allow the protest to relocate to another site. Although a splinter group, Reasonable Solutions, has been given permission to protest during the day and evening on Thomas Payne Plaza, Alford-Fowler said that the overnight camp is necessary for the movement to succeed.
"Regular demonstrations don't work anymore," she said.
The protesters waited until Police Civil Affairs Unit Capt. Bill Fisher issued his third and final warning, then quickly spilled into the street, where many of them remained for several hours. Police stood like sentries in lines surrounding City Hall. Groups of officers in riot gear crisscrossed the plaza.
In a brief meeting with some reporters, Commissioner Ramsey was asked if he thought the night was a success.
"It's still early," he said.
Behind him, a woman protester who had climbed a tree to avoid the police, clung precariously to a thin limb as police ordered her to come down.
After about 20 minutes, officers persuaded her to come down, brought her a ladder and escorted her to the street.
At about 2:30 a.m., with temperatures dropping and the wind whipping up Broad Street, nine police on horseback joined the dozens of officers on bicycles to press back against the increasingly agitated group of protesters.
The demonstration divided and migrated until at one point, it seemed as if crowds surrounded City Hall. Shouting and chanting could be heard from blocks away. Several attempts to break through police barricades succeeded, raising tensions.
Helicopters thumped overhead, fire fighters stood by their trucks, poised to use water hoses, and squads of officers carried plastic shields and billy clubs.
But compared to the violent confrontations that have occurred in other cities between Occupiers and the police, the night's pain was minimal.
One woman suffered an injured foot when a horse pressed back against a crowd. Three police officers were hurt, two while making arrests away from the plaza and one who was cut taking down a tent.
Police arrested six protesters at about 3 a.m. when they tried to force their way back towards Dilworth Plaza.
By 4:30, when the crowd made its way to 15th Street between Spring Garden and Hamilton streets, the chanting voices had grown hoarse and patience, thin. One officer with a bicycle rammed into a Occupy protester who was blocking the sidewalk. When the young man cried out and threw both hands in the air to show he was not resisting, a nearby policeman asked his colleague to back off.
At about 5 a.m., 44 protesters, corralled on one side of the street, were arrested.
Among the weary civilly disobedient standing with hands cuffed behind their backs, waiting to be led into the waiting Sheriff's buses, was Steven Venus.
"It took 20 cops to tear down my structure," he said. "I'm pretty proud of that."