If any of you know anything about horses, I could use your help with a scene I'm writing.

The bad guys have brought an army northward, ill-prepared for the harsh climate. Winter comes early. Snow piles ups. Temperatures are continuously below freezing. They have to camp outside, huddled around fires.

My question is...how quickly would horses succumb to the weather?

As I said, the army is ill-prepared and they didn't bring much in the way of supplies or fodder, so the horses are basically forced to eat what they can find.

Would they die of hunger before freezing to death? Or would the horses tolerate the freezing cold? I'm not sure how hardy horses are in such regions.

Any thoughts are appreciated.