The Fall of the Undefeted Cavalry

Well, it takes a certain kind of stupid to attack a Dwarf force on their home turf. I mean, what are you gonna do, they probably have better weapons, better armor, more fall back positions that a squirrel has nut caches, and that isnt even mentioning everything that they have probably done to prepare the are to defend it. Unless you have a God on your side you are basically doomed to fail.

— Jasper Cameron, Leader of the Bronze Ravens.

There is a story told to all military commanders as a warning of hubris. The year was 3419. The Undefeated Cavalry of King Johan was making its way across the land. After some conquest or another, he set is eyes on the dwarf stronghold of Osect. Known for having veins of both mythril and adamantite, as well as a deep supply of iron, and a nearly endless supply of coal, Johan decided that he would take their forges to make his army even more unstoppable by improving the equipment that they had. This would prove to be the end of his nearly 2 decades of conquest.
There is a reason that Dwarf Strongholds are considered to be impregnable. You see, Dwarfs dont wait for people to attack before preparing their defenses. There are layers and layers one must penetrate. (also who in their right mind would think that cavalry was the way to go when attacking people who literally live in underground tunnels.)
But the dwarves of Osect decided to play into the hands of Johan, at least that is what he thought, for he had not been defeated yet, and even Dwarf strongholds are vulnerable to a long enough siege.
So the met in a valley leading to the entrance proper or Osect. The Dwarven shield wall was set, and the cavalry charge had started, shortly before midday. Well, that was the plan, less than 20 yards from the dwarves, things started to go wrong. the left side of the wedge started to falter and collapse. Sappers can be used defensively you see.
No one that doesn't know what they are looking for can find the tunnel of a dwarven Gopher, but that doesn't mean that they aren't there. Indeed it was these very tunnels, dug for just such an eventuality, that were proving to be so hazardous to the forces of King Johan. As unthreatening as they may sound, dwarven Gopher squads are experts in preparing a battlefield. Just as a normal gopher warren can prove hazardous to horses, multiply that by a thousand, and then make it smart.
You see, anyone can break the front line of a cavalry charge, but to break a whole charge takes something else. first, you break the middle, causing chaos in the back, while the front, deafened by the pounding of hooves know nothing of what has happened behind them. Then you take care of the rear, in this case, well, lets just say you are better off not hearing about what happens when almost 12 tons of spiked wheel rolls over flesh and blood. The Juicer requires only simple math to deploy, if it has been tested even once, you know when it will get to where... and well, there is a reason it is called the Juicer.
Then all you have left is the front. Those expecting to be backed up by the rest of the wedge behind them. A dwarven shield wall is more maneuverable than one might expect. The dwarves proceeded to do what they had practiced thousands of times, they collapsed back, and eventually surrounding the last of King Johan's Undefeated Cavalry. Then, well... 12 horses survived.
Whether this was do to the planning of the dwarves of the idiocracy of King Johan is up for some debate, but there is a lesson here either way.