The Formed Charge - A Video Tutorial: Part 1
It's all well and good being told how to charge properly, but you can't always get it to work for you. This guide is written mainly for Kingdoms, but everything in it is equally applicable to Medieval 2: Total War will show you exactly how to get the formed charge to work with video examples, allowing you to see what it looks like when it goes well or badly. This should hopefully allow you to work out what mistakes you are making (if any) and correct them. In Part 1, frontal charges are discussed, concentrating of the choice of target. Experienced players may wish to skip this part, as it is fairly basic.
For simplicity, I will be using the Teutonic Ritterbrüder as it is a strong heavy cavalry unit with a powerful charge. The enemy will vary with the situation.
Picking Your Target
The simplest use of cavalry is the frontal charge, because it requires little finesse to do it. Strategically, it can be a little dodgy, especially against a competent opponent, but it can be a very useful way to take out an important enemy unit before it can be put to its intended use of sending your men to meet their maker. For this reason and because it can take your enemy by surprise (note can, not will - surprise cannot be guaranteed), it is worth taking a little time to study it. This type of study is not the boring educational kind, it generally involves charging knights at things and stepping back to watch the carnage afterwards - my favourite kind of study!
Let's start off with something easy. - like Peasants. Now while they are weak in melee, they do resemble many low to mid-level missile units in melee. As one would expect, the knights are the clear winners, but the thing that should be noted is the speed with which the victory is gained. In the time that it takes for the charge to hit home, the enemy are wiped out completely. If the enemy have one decent missile unit and you are able to quickly and cleanly take them out before they can kill too many of your men, then you have saved a lot of lives in your army. This is more important in a long campaign, where minimising your casualties is as important as winning the battles - no-one really wants a pyrrhic victory. In battle where you are outnumbered and out-shot, taking out a missile unit or two before they have expended the majority of their ammunition will even the odds up somewhat, reduce your overall casualty numbers and significantly increase your chances of victory.
Moving on to Heavy Infantry, these guys are the real meat grinders of the army who are going to chew up your infantry if you give them the chance. If the enemy only have a unit or two of heavy infantry and lots of militia units, then taking them out early is going to punch a huge hole in the enemy's offensive capabilities. If you are going to besiege an enemy castle next turn, you'd rather see Peasants and Spear Militia on the walls than Dismounted Feudal Knights for example. In this example, I merely charged my knights in and left them to the slaughterfest that inevitably followed. Ideally, I would cycle-charge by either retreating and regrouping the knights or by retreating them at an angle and charging in another unit (this gives the enemy less reaction time, but is very intensive on micro-management). Again, the knights win with minimal losses. I would certainly swap a knight or two for a whole unit of Armoured Swordsmen, both on economic grounds (cost of killed/captured men) and the fact that my knights still have the numbers remaining to punch big holes in enemy units in the same battle while the enemy infantry is either dead or fleeing.
Looking at militia level spearmen, the knights win again. Notice though that they do not smash through the enemy lines, rather they break the unit. In a full battle situation (rather than an unbalanced one on one), this would leave the knights open to envelopment from both sides by the adjacent infantry units, especially if there is a reserve kept back to shore up the lines if necessary. Without the benefit of the charge, they will be lucky to withdraw with half of their men left. Remember that this is the absolute elite of knights against very low end militia infantry. Spear Militia can be spammed very easily because they can be trained and retrained at practically any city (and the same can be said for Sergeant Spearmen or equivalent units recruited from Castles), while it is very difficult to retrain your Ritterbrüdern especially if there are lots of enemy Priests in your provinces. Basically what I'm saying is that a frontal cavalry charge at people holding long pointy sticks may carry you to glory, but there are generally better ways of winning the battle - specifically ways that don't lose you your most expensive and most powerful units.
There is one use for a frontal charge into low-grade spearmen though - reverse psychology. The AI doesn't think as such, it reacts extremely quickly to a complex set of checks, so it's better to be conventional against it unless you are utilising a weakness in its programming. Against a human though, you have someone who is basically like you at the other end. If something unexpected happens, then they have to re-evaluate what is going on before they can react to it. If they haven't covered a flank with their anti-cavalry units because there are a couple of units of Spear Militia on the end, then it might be a good idea to charge them with your knights to see what the enemy does. It's audacious, unexpected and can really rattle the enemy if you retreat them smartly and hit him somewhere else (preferably on the other flank) immediately afterwards. If you are far enough ahead in the battle that you can afford to throw away a unit of elite cavalry, then it might be worth considering as a way of distracting the other player sufficiently that you take the initiative and can roll up his army from one side (or something). Former chess world champion Mikhail Tal often played moves that while not the best from an overall strategic sense, he considered would cause maximum discomfort for a particular opponent, thus getting under his skin and reducing the quality of his game. This move is an example of this, but be aware that it is just as likely to backfire on you. It's just a thought, but you never know when it might come in handy...
Charging elite spearmen with cavalry is not wise. As you would have thought, it is playing straight into the hands of the spearmen. In this example, the Papal Guard formed a Schildtrom, which actually doesn't help against a frontal cavalry charge, since it is a formation intended for dealing with massed enemy troops completely surrounding you. They still won comfortably though. Do not attack them while braced, as the charge bonus is reflected onto your cavalry.
Now this one is mainly gratuitous knight slaughter, since I'm sure most people don't charge head on into enemy pikemen (at least I hope you don't). Basically, don't do it or this happens. Consider charging into Longbowmen cowering behind stakes in the same way - it doesn't work if you attack from the front.
In this section, it has hopefully been proven that to effectively use knights, they should be targeted at anything that doesn't hold a spear and that a formed charge will obliterate most enemies it meets. This is useful because with heavy cavalry, you can take out a valuable enemy unit in a very short time, thus turning the tide of the battle in your favour one step at a time. However, a "suicide charge" into low-grade spearmen can distract a human general if you are lucky, but do not count on it working.