"What a beautiful land you will be for the enemy."

The most important battle you've never heard of took place over six days in August, 636. Arab muslims, united for the first time under the Caliph had seized Iraq from a weakened Sassanid Persia, and then invaded Byzantine Syria.

This was too close for comfort for Emperor Heraclius. It was one thing for these new invaders to harry the Empire's ancient Persian enemies. It was another thing entirely to find them a few day's march from his residence at Antioch. He gathered an enormous army from across his empire - ancient sources are notoriously unreliable when counting the number of troops, but his force numbered no less than 20,000, and may have had twice that. Arab chroniclers put the number at 80,000.

But the very size of the force contained what would be the seeds of its own failure. While the elite Imperial Kataphraktoi (heavy cavalry) were the core of the army, there was no way that even the Empire could afford tens of thousands of them. They fleshed out the rest of the cavalry with auxiliaries from subject kingdoms. The highly mobile light cavalry came from the Christian Arab kingdom of the Ghassanids.

The problem is that the Ghassanids were considered heretics. Adherents to the Monophysite belief (the belief that Jesus had only a divine nature, not a dual divine and human one), they were not fully trusted. Long standing tensions between them and the Imperial government had relations swimming in a poisonous mixture of contempt on one side and grievance on the other.

When you add poor generalship to the Byzantine side (General Vahan fought on ground chosen by his opponent, Khalid ibn al-Walid, the "Sword of God"), the battle went south for the Byzantines. Using interior lines, Khalid shifted his mobile reserve from location to location to thwart his superior adversary. Even so, it was a near thing, and the Battle of Yarmouk is perhaps the longest meeting engagement in ancient history.

But the Arabs were united in purpose, and their opponents were divided among themselves, and on the sixth day the Imperial Army cracked. Unable to make its divisive components support each other, they were essentially defeated in detail and routed. The Empire was exhausted by the expense of fielding the massive force, and couldn't counter the victorious Arab army. Provinces fell like dominoes, and the Emperor was forced to flee by ship to Constantinople. As he boarded, he gazed back at his beloved Syria and lamented:

Farewell, a long farewell to Syria, my fair province. Thou art an infidel's now. Peace be with you, O Syria – what a beautiful land you will be for the enemy.

Palestine, Jerusalem itself, Egypt, and North Africa were gone in a decade, and the Empire faced a slow decline into oblivion.

Mistrust among allies is a sign of impending disaster. We see that distrust - in the Washington Post, no less - surfacing between the Democratic House of Representatives and the White House:

"What they wanted to do is separate themselves from us," Pascrell said Wednesday. He accused the White House of wanting to preemptively pin the blame on lawmakers running poor campaigns should Democrats lose the majority and not on Obama's own sagging approval ratings.

At the Tuesday night meeting with Pelosi, lawmakers groused that the White House was taking them for granted. Pascrell was especially vocal and punctuated his complaints by reading Gibbs's comments word for word in front of the caucus. After he spoke, Pelosi interjected. "I disagree on one point -- I think you were too kind to Mr. Gibbs," she said, according to Democrats familiar with her comments.

You can cut the distrust with a knife. While it's made worse by the poor generalship displayed by the Obama Administration, the distrust for many runs deep. The Administration is filled with the politically Orthodox - hard left, urban coastal machine pols. They despise the axillary troops that gave them the victories of 2009 and early 2010 - the Blue Dog Democrats. They despise them because they are heretics, supporters of anathema like the Second Amendment, strong national security, and (relative) fiscal sanity. They are barbarians from benighted border provinces like North Carolina and Arkansas.

The Blue Dogs know that they're not trusted. They think that they're canon fodder, and that the Imperial Court - Obama, Rahm Emmanuel, and Gibbs - don't respect them. They're probably right.

Right now, the Democratic Party holds a commanding advantage, but they struggle to exploit their weight of numbers because of internal religious wars. At the very moment that their enemy's strength is waxing, they find internal divisions within their ranks hindering a cohesive response. Contempt is met by mistrust, and the hour of the battle draws nigh.

Jabalah ibn al-Aiham was the last king of the Ghassanid Arabs, and commanded their contingent at Yarmouk. Abandoned by the Empire following the disaster, he converted to Islam. At least there, he wasn't despised for being an Arab.

One wonders how many surviving Blue Dog Democrats will consider this course - joining the other party, because their current one doesn't quite accept them. November is still a long time off, but interesting political events won't end with the election; they'll start with it.

Farewell, a long farewell to Carolina, my fair province. Thou art an infidel's now. Peace be with you, O Carolina – what a beautiful land you will be for the enemy.