So far, we have only learned about how to play with general infantry plus light cavalry. However, we have not learned maybe one of the most important unit type in Napoleon Total War, which are cavalry. Even that to imply the importance of Cavalry in Napoleonic wars, i would like to share a quote about what napoleon said at that time. Cavalry should charge at start of the battle, during the battle and through the end of the battle. Cavalry must in all opportunities must charge. Another quotation from Napoleon is, to imply the importance of artillery to cavalry. He said, "Artillery is more important for cavalry than infantry. Because cavalry has no return fire for their defence, hence they depend on the saber. I hope these have explained the importance of cavalry to you, in both real Napoleonic Wars or the game, Napoleon Total war.
So how to use the heavy cavalry requires a bit of skill in charging. As Napoleon says, cavalry charges are always necessary. However, there are great number of players who tend to charge only once per cavalry unit, and which can be in any time during the battle. Also that this charge of theirs is not intentionally, because they just mean the cavalry to attack. They double click on the enemy for the cavalry to attack fast, means running to them, not charging. So the cavalry attacks the unit, and continues fighting with the unit during the combat. This is really a good way to waste your cavalry units on crap units. The way you need to do it can be best learned in medieval total war, whereas cavalry charges are the basis of the new style, which is the main style of medieval wars, consequently, also of medieval total war. You, in medieval total war, sooner or later learn how to use charge of the cavalry efficiently, because without that, winning a battle is really hard. So, you need to charge in a unit, break their formation and deal maximum damage until the charge ends, then retreat back in to charging distance. This distance can be adjusted accordingly to the time that the unit is likely to reorganize, for you might not want to receive another salvo from the whole line of infantry on your cavalry. Since cavalry are the units who can most easily be shot down, because of their big volume, since including the horses.
However, not all the cavalry are as good as each other in charges, which means you have to be careful on what type of cavalry you have. You might be used to one type of cavalry and yet have the other type where you can not apply the ways you used for the other one to this one. So, to make sure and guarantee that you will win the battle, you will need to know the tactics of all types of cavalry. The benefit of it can be also that it brings you to intentionally select which type of cavalry you want to recruit on the campaign map, depending on what are you planning to do with them.