The Rohirrim, why horses?

[Lastande Took]

Originally Posted by Morthoron

Amusingly, that was not always the case in Middle-earth (and certainly not the case for the flower of French chivalry at Crecy and Poitiers). For instance, the Numenorean infantry was the most formidable force of the 2nd Age. Sauron's legions folded up their tents and headed for the mountains at the very sight of them.

I didn't know about the Numenorean infantry. They sound pretty cool.

The "flower of French chivalry" lost most of the advantages of horseback combat when they decided to use Clydesdale-sized warhorses and loaded themselves and their mounts with a couple hundred pounds of armor. In doing so, they became more like the equivalent of modern-day tanks. The Rohirrim, on smaller, lighter horses, were more like helicopters - able to dart in, take advantage of their elevated (compared to infantry) position, and get back out quickly if needed. In addition, the horse itself could be used as a weapon, knocking enemies out of the way with 1,000 pounds of momentum. Not as much as a European knight's 1,800 pound armored beast, but still effective.