The purpose of the cavalry is to strike the enemy from the side or behind after they've engaged the main infantry, allowing the speed and sheer power to cut the enemy army in half. The Dothraki ride out on their horses to confront the Wights head-on and are quickly decimated by the horde, primarily because that's not how you use horsebound cavalry. RELATED: Game of Thrones Basically Turned Into World War Z For An Episode So, it's very surprising to see that is indeed the first course of action for the heroes. Going up against the seemingly limitless undead warriors fighting for the Night King, an outright charge against the endless horde isn't going to be super effective. They're prepared for the siege, or as prepared as they could possibly be.
So, the living have solidified their defense inside Winterfell.
