At the head of your elite cavalry, you press your horse up the rough, steep slope. A hail of javelins comes from the waiting English line as you draw near, and many of your men are wounded and some killed; horses scream in pain and terror. Then you are into the housecarles, and their terrible axes go to work on horseflesh. Horses fall forward and crush Englishmen, or backward rearing and falling they mangle and disorder your line. It is more like a riot than a battle; order and discipline are momentarily non existent. Fighting for your life, all conscious thought of reaching Harold's standards is banished: your horse is killed and you kick free of the stirrups and land on your mailed feet. After a desperate moment in which the immediate housecarles did their best to kill you, you manage to back away from the fighting long enough for one of your knights to dismount and offer you his horse. Then you are at it again, pressing right into your foes and striking down all who come within reach of your sword arm.
The rout started because a rumor spread that you were slain. Your Normans began to give way, and your shouted commands to stand firm were heard only by a handful near you; the rest panicked and turned and fled down the slope, their shields covering their backs. You are swept away with the press of routing horsemen.
Once out of range of the fighting zone, you can take stock of the situation more clearly: it is far worse than you thought: your whole army is either routing or withdrawing. It is not from any act of yours that they finally stop running away. Perhaps it is only collective professional pride. Whatever it was that stopped the rout, you don't care, you are just grateful.
You spend a while getting your men back into some order. Incredibly, Harold's main force is still on the ridge: why didn't they pursue en masse? You were finished if they had done so.
There was a pursuit, but only a limited one over on the left: the Bretons are into the marshy ground, fighting with masses of Englishmen from the right wing. The Breton rout tempted them down off the hill, so it seems.
You take a body of Norman cavalry and ride over there, coming like the wrath of God into the flank of the pursuing English. That fight is soon over, and the Bretons are coming back. Your army is sorted out and seems strong enough still; but the English line is looking thinned out, especially on their right. Now:
Order the French wing to fake a rout, to hopefully draw down the English left.
Bring up the marksmen and have them shoot until the English line wavers
Call it a day and regroup at Hastings. After a good few days rest you should be ready to take Harold on again.