CAIRO — A year ago, Tahrir Square was a carnival of unity — Egyptian protesters stood Christian with Muslim, Islamist with leftist, women with men, rich with poor — for the common cause of bringing down Hosni Mubarak’s authoritarian regime.

Now Mubarak is gone, and so is the show of solidarity that ended his regime and galvanized other Arab Spring rebellions.

The revolutionary movement has fragmented into rival blocs overseen by an all-powerful military council.

The square itself is a bullet-pocked battleground where a small, perpetual demonstration snarls traffic and chokes downtown Cairo businesses.

Within this mosaic, Islamists have emerged as Egypt’s dominant new political force, much to the dismay of liberal protesters, whose Western-style demands sometimes run counter to strict religious teachings.

As the competing groups bicker over parliamentary posts and the ruling Mubarak-era generals wield their authority, revolutionary activists say their dreams of speedy democratic reforms and civil liberties seem as distant as ever.

“We didn’t win,” said Mohamed Abla, a well-known painter and vocal critic of the military council. “The revolution has moved into another stage now, and it seems we still have to fight and fight and fight.”

After a bloody and difficult transitional year, Egyptians are expected to stream back to Tahrir Square by the thousands today, though there’s no clear revolutionary agenda for the commemoration of the first protests last Jan. 25.

Some groups call for a renewed uprising to bring down the military council, while others want a somber remembrance of the “martyrs,” the estimated 1,000 protesters who were killed in the past year’s uprising and many subsequent spasms of political violence.

Liberal blocs are worried that Islamists will turn the event into a victory rally after winning more than 70 percent of parliamentary seats in the first post-Mubarak election.

The Muslim Brotherhood and the literalist Salafist factions, meanwhile, are nervous that the gathering will lead to clashes with government security forces, forcing Islamists yet again to choose between supporting fellow protesters or staying in the good graces of the powerful generals.

The discord surrounding the anniversary mirrors the frank talks going on in closed political negotiations, with the newly emboldened Brotherhood pulled in at least three directions — left toward established liberal parties, right toward the ultraconservative Salafists or into a risky partnership with the status-quo generals.

Women, Coptic Christians and the revolutionary youth barely register in power-sharing negotiations, those groups complain.

The military has unveiled plans for its own commemoration of Jan. 25, which it has declared a national holiday. Plans include a nationwide air show, including flyovers by warplanes.