Michael Wahid Hanna in The Atlantic:
When armored personnel carriers filled with soldiers began making their way into the heart of Cairo and other cities in Egypt on Friday January 28th, they were greeted with receptivity by protestors, who saw in the much-respected military a potential ally in their uprising against the regime. No doubt, the recent experience in Tunisia, where the military stepped in resoundingly on the side of the demonstrations and hastened the fall of the repressive regime of President Ben Ali, was fresh in their mind. The Tunisian military had intervened against the police forces, burnishing their image as popular heroes who shared the patriotic concerns of the brave Tunisians who defied the regime. The scenes that unfolded in Egypt made clear that the protestors there hoped to force a similar split between the security forces, run by the Ministry of the Interior, and the military.
While Egypt's military is no longer an active fighting force, it still retains more credibility as a public entity than Egypt's civilian institutions, crippled after years of neglect and one-man rule. In recent years, even some democracy activists, despondent from years of state repression and ineffectual organizing, have seen the military as the last hope for Egyptians against Mubarak's efforts to orchestrate his son, Gamal, as successor to the presidency. Now that demonstrators have overwhelmed the police forces and built popular momentum, the military, were it to shift its allegiance from Mubarak to the protesters, could effectively end the regime.