The military’s unparalleled position in Egypt’s public life is a result, in part, of the perception that it is a dispassionate defender of the country’s broad public. The military made that face particularly visible in recent days, sending its jets into the sky above the fray—flying triumphal missions that left contrails in the shape of hearts, or the colors of the Egyptian flag, above Cairo…

But in intervening directly as jilted Islamists demanded Mr. Morsi’s reinstatement, the military runs the risk of being seen as siding against Islamists and vindicating many Egyptians’ fears of an impending civil war.

On Friday evening, thousands of Morsi supporters attempted to use the October 6 bridge to reach Tahrir Square, where thousands of the former president’s opponents were holding rallies to celebrate Mr. Morsi’s ouster and “defend” the revolution.

According to witnesses, the opposing sides clashed on the bridge. Two witnesses said that Morsi opponents fired automatic weapons against the pro-Morsi arrivals, and the sound of repeating fire could be heard in the area. Shortly after, according to witnesses, the sides appeared to run out of ammunition, and turned to throwing rocks and fireworks.