I am just curious. In most games spear infantry is a "counter" against cavalry. How does that really work anyway?
Any clips on actual cavalry fighting infantry that's historically accurate would be awesome. 3D simulation is great.
The infantry sets their spears, meaning bracing them against the ground, to present a barrier to the charging horsemen. The long spears, also known as pikes, when held in a tight formation provided a spiked wall that would challenge mounted opponents. Some horses would balk when encountering the pikes while others would be impaled. The goal was to unhorse the rider and have infantry men kill the stunned riders with clubs and/or short swords.
This tactic was particularly effective the battles of Stirling Bridge (1297) and Bannockburn (1314) where Scottish pikemen defeated heavy English cavalry. In both battles, using the spear walls in an area where cavalry movement was limited was a force multiplier. Other battles, such as Agincourt (1415), Crécy (1346) and Poitiers (1356), combined the spear wall tactic with missile weapons along with terrain advantages to win decisively.
Cavalry counter tactics were to flank such formations and get behind them rather than to charge head on. That's why terrain played a big role. In situations where pikemen didn't have the terrain on their side, they were a lot more likely to be flanked and routed. Of course, it took a while for traditionalist knights not to charge head-on into disaster.
Edit to add video reenactment/description of battles
Spears are (relatively) long ranged weapons to use against cavalry. Bows and arrows are even better (as at Crecy and Agincourt in France), but only if they can be fired at a high rate, and at long range. Most infantrymen were not skilled enough to do this, which is why they used spears. They could try to kill the horse or the rider, but usually the horse was the bigger, more vulnerable target. Kill the horse, and the rider comes crashing down, at your mercy.
The cavalry had the advantage of speed. In some cases, they could gallop behind the defending lines faster than the infantry could turn around, and take the infantry in the rear. That's why terrain was so important. Flat, easy, terrain favors the cavalry. Hilly, forested, or otherwise broken ground slows the cavalry charges and helps the infantry. At Agincourt, there was a rainstorm before the battle that turned the ground into mud. It slowed both British infantry and French cavalry, but the cavalry suffered RELATIVELY more.
A group of men armed only with spears were usually not enough to fight cavalry by themselves. The successful ones usually had something else going for them, such as armor and/or shields. Sometimes, they would "mine" ground against the cavalry, by digging "potholes" or setting up sharpened stakes in front of the infantry lines.