Yesterday, Mohamed Morsi insisted that he would sacrifice his life for his “constitutional legitimacy.” A few hours later, the Egyptian military upped the ante by pledging their own blood to free their nation from the Muslim Brotherhood’s autocracy:

According to CBS News, they’re not bluffing. Army chief Gen. Abdel-Fattah el-Sissi called a meeting of his general command with just hours to go before the deadline of his ultimatum to Morsi to either reach an agreement with the opposition for reform, or find himself and the Muslim Brotherhood ejected from power:

A Defense Ministry official said Wednesday that army chief Gen. Abdel-Fattah el-Sissi was meeting with his top commanders, hours before the military’s deadline to the president and opposition to resolve the nation’s political crisis was set to expire.

The official, who gave no further details, spoke Wednesday on condition of anonymity because he was not authorized to brief the media.

Even so, Morsi’s not budging. And the violence has already started, although so far it’s not gotten out of hand:

Sporadic bursts of automatic gunfire shut down streets in central Cairo overnight as supporters of President Mohamed Morsi clashed violently with opposition protesters outside Cairo University, where the president’s supporters had gathered. At least 16 people were killed and more than 200 wounded in the clashes that erupted late Tuesday night and carried into the early hours of Wednesday morning, as Morsi delivered a defiant televised speech that made clear he would not back down.

With only hours to go until the Wednesday deadline, Egypt was quickly hurtling toward a showdown between its powerful military and the Islamists, including Morsi, who swept to power in elections last year. Morsi’s backers in the Muslim Brotherhood have vowed that they will not go quietly if their president is forced out. …

The speech represented a direct challenge to the nation’s military and a signal that efforts to mediate the crisis have so far failed. Earlier on Tuesday, Morsi met with his defense minister, Abdel Fatah al-Sissi, in an apparent bid to reach an accord.

Shortly after Morsi’s speech, a message was posted to an Egyptian armed forces Facebook page saying, “We swear to God that we will sacrifice even our blood for Egypt and its people, to defend them against any terrorist, radical or fool.”

Perhaps neither side is bluffing.  If that’s the case, the Muslim Brotherhood had better be prepared to deal with a hostile military — and ordinary Egyptians had better find ways out of the crossfire.  The questions may soon be how much discipline Sissi can expect from his military units and commanders, and how much backbone the Muslim Brotherhood rank and file have for a heavy-arms fight. Morsi and Sissi may be underestimating those capabilities in their enemies and overestimating them in their own forces, which would precipitate a violent resolution of those questions.  We’ll probably know sooner rather than later now that it’s clear that neither side will budge until the last moment, if at all.

Update: With an hour to go before the ultimatum expires, this report from Richard Engel shows how serious the army is — assuming it’s accurate:

Sources #army in charge state tv building. Staff being told to go home early, leaving only essential personnel. #egypt

— Richard Engel (@RichardEngel) July 3, 2013

If they’ve already seized the broadcast stations, that sounds like action is coming very soon.