They fight to the death I'll tell ya, well, at least "most" of the time. I've had one unit in Large settings (81 men per unit) route when surrounded by the Senate Imperial army in the Roman province fields, when only 17 of them were left.

But then in MP, I had a unit of Spartans fight to the last map against 1,000 enemies in the streets of a city. When only two remained, still not routing, they were pressed on their backs against a wall, me & Torque watched them cheering them on, (though they cannot hear us or anything), and they killed a count of 13 more enemy Roman legionaries by themselves, and then were both killed.... pressed against a wall with back facing it... 500 eemies left alive infront of them pressing them up against the wall... 159 fellow men in armies dead (the rest of their unit)... and they still fought to the death!

Me & Torque bring those two fella's up everyday that we get on to play that, lol! Talk about being remembered!

I think that when the enemy MP player saw this, he knew he would not win that fight.