All year, secular liberals have accused the Brotherhood -- the most powerful political party in the country -- of playing footsy with the military. Finally, however, the Brothers broke with the military over the legal role of the armed forces, rather than, as many expected, over whether Egypt would be defined as a secular state.

Demonstrators from across the spectrum stayed on script on Friday, all demanding that the military honor its promise to leave power. Fringe elements, like the jihadis who waved photos of Osama bin Laden, were jeered even by fundamentalist Salafist protesters. When some zealous Islamists chanted for sharia, they were silenced by their peers.

"It only feels a little bit like Kandahar," joked secular activist Rami ElSaid, from the April 6 movement. "I am happy about today."

At nightfall, that unity frayed and snapped: the Islamists packed up and went home, leaving only a small number of secular activists to sit in overnight in the square, still demanding that the military agree to surrender power to an elected civilian president by April 2012.

Police smashed into a corner of the square on Saturday morning, beating the protesters that remained. The group was so small it wasn't even impeding traffic, and it was attracting almost no attention. The police response did, however, and by midday Tahrir was a war zone. On Saturday evening, the police cleared the square after a day of shooting people with rubber pellets, often in the face, blinding several, and enveloping the entire square in tear gas. Within an hour, the crowd had reoccupied the square. On Sunday, the military joined the charge, clearing the square in concert with police just after nightfall. Again, within an hour, demonstrators had retaken Tahrir.

The toll as of Monday morning, according to the Ministry of Health: at least 2,000 injured, a minimum of 20 dead according to the Health Ministry, and Egypt's parliamentary elections in jeopardy.

These clashes have felt different, however, from others since Mubarak's resignation.

For starters, the police were clearly aiming at people's faces, unleashing a constant barrage of rubber bullets and pellets along with the more customary tear gas. Doctors said they found live ammunition in many of the dead, despite government denials that its security forces are using real bullets. Unlike previous clashes, the military and police worked together to fight the demonstrators, most obviously in the Sunday evening assault on the thousands in Tahrir. And a potent mix of people were willing to fight the increasingly nasty police: poor kids and rich kids, seasoned activists and people who'd never been to a demonstration before, bearded Islamists and secular women.

The determination of the crowds is unlike anything I've seen here since the original uprising, when wave after wave of demonstrators overpowered riot police and subsequently stood firm under an orchestrated attack by gunmen and cavalry on horses and camels.