Morkus from Orkus
Oh yeah, I also tend to think the Dothraki charge was dumb. In real life, as far as I know, much of the power of cavalry charges come from its ability to break lines through a combination of fear and momentum. The Dothraki charged headlong into a literally *wall* of undead, and the only thing that accomplishes is being surrounded by zombies and quickly dying to their counterattack. They should not have even attempted that without knowing what the enemy battle lines actually looked like.
Heavy Cavalry would smash into the lines to break them. Light cavalry like the Dothraki would be used to hit the flanks of the enemy and peel away, harry retreating foes, or to screen and allow your troops to retreat. All of those depend on knowing exactly where the enemy is.