Cairo — Hosni Mubarak, the Egyptian leader who for nearly 30 years was the resolute face of stability in the Middle East, died on Tuesday, the country's state television said, ending his days after a swift and ignominious tumble from power in the Arab world's pro-democracy upheaval. He was 91.

Throughout his rule, he was a stalwart U.S. ally, a bullwark against Islamic militancy and guardian of Egypt's peace with Israel. But to the tens of thousands of young Egyptians who rallied for 18 days of unprecedented street protests in Cairo's central Tahrir Square and elsewhere in 2011, Mubarak was a relic, a latter-day pharaoh.

Egypt's former President Hosni Mubarak sits inside a dock at the police academy on the outskirts of Cairo, May 21, 2014. Reuters

They were inspired by the Tunisian revolt, and harnessed the power of social media to muster tumultuous throngs, unleashing popular anger over the graft and brutality that shadowed his rule. In the end, with millions massed in Cairo's Tahrir Square and city centers around the country and even marching to the doorstep of Mubarak's palace, the military that long nurtured him pushed him aside on Feb. 11, 2011. The generals took power, hoping to preserve what they could of the system he headed.

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Though Tunisia's president fell before him, the ouster of Mubarak was the more stunning collapse in the face of the Arab Spring shaking regimes across the Arab world.

He became the only leader so far ousted in the protest wave to be imprisoned. He was convicted along with his former security chief on June 2012 and sentenced to life in prison for failing to prevent the killing of some 900 protesters during the 18-day who rose up against his autocratic regime in 2011. Both appealed the verdict and a higher court later cleared them in 2014.

The acquittal stunned many Egyptians, thousands of whom poured into central Cairo to show their anger against the court.