Cavalry was quite capable of engaging in a full frontal charge against an enemy unit during the period.

However such an action would generally not be considered advisable in most circumstances. If taken in isolation where a cavalry regiment is forced to charge exclusively at an enemy battalion in line that is ready and prepared to meet them with no option to flank then it would be a matter of debate.

In such an instance it would come down to any number of different variables such as the quality of the ground both forces occupy the units in question, their commanders, how well supplied these units have been over the past few weeks and of course how brave they are. A battalion of untested and poorly equipped Spanish line would be swept away by a unit of veteran French curriassers in almost any circumstance.

Of course, to attempt to use an instance in isolation is an absurdity. As I have already mentioned there are a simply endless list of variables already without considering the tactical and strategic positions of the units involved.

So whilst such charges were possible they were far from commonplace.

So in reality, how were cavalry used and how did they perform?

First I will make a distinction between the types of cavalry, there are heavy cavalry such as the Horse Guards of the British Army, and the Cuirassiers of the French, Austrian, German and Russian armies, and the light cavalry consisting of Hussars, Lancers and Light Dragoons.

Such distinctions are loose at best. In ideal circumstances heavy cavalry are large men mounted on large horses in most cases wearing armour and wielding long straight heavy swords. Light Cavalry are of course the opposite with generally smaller horses that tire less easily and slashing sabres. Heavy cavalry was intended for short distance charges. Devastating a section of enemy line and wreaking havoc. Their horses tired easily and required much higher maintenance than their lighter counterparts and so where conserved to be unleashed at a pivotal moment. Lighter cavalry was used to scout and act as piquets for the army on campaign. They were also deployed on the battlefield too to act as a harrying force or a highly mobile reinforcing unit.

However the distinctions were never as clear cut, especially for armies that suffered from a shortage of cavalry like the British in the peninsular or the French after their invasion of Russia. The British for example used Dragoons for most things as a sort catch all medium cavalry that performed all roles.

The primary defence against cavalry for infantry and artillery was the square. Artillery seeking shelter inside a nearby square. Now the advantage of square is threefold. Firstly it presents no flank for enemy cavalry to attack, it is surrounded by bayonets presenting a hedge of spike upon which no horse will throw itself and only lancers with being able to reach through to attack the infantry and thirdly there is another two rows of men who can give fire against nearby cavalry without fear of retaliation. There are only a few instances of cavalry breaking into a square at least one is where proper protocol was not observed and the men in square fired at charging cavalry from far too close. Causing a dying horse and rider to be carried through the square by the momentum of their charge and opening a hole.

Any enemy line or artillery that was caught unawares or unable to react due to disorder or incompetent command would suffer dearly. Cavalry would get around behind the men and they would scatter and be ridden down in their attempt to flee. Initiating a flight response in thousands of well drilled men and reducing a formidable brigade to corpses and fleeing men.

Cavalry also had tactics for attacking enemy formations, whether in line of square. They would attack by echelon. Whereby the cavalry is split up into its squadrons who follow slightly behind each other in a diagonal line. This would hopefully cause the enemy to expend the majority of their shot on the first squadron who would then pull away and allow the next squadrons to attack whilst they were unloaded.

There are plenty of instances of cavalry defying the odds and forcing breaches in square or committing to incredible assaults against all odds that ended in success or failure. The French cavalry attacking British squares at Waterloo for example.

Normally however the best use of cavalry was to assault wavering or disorganised troops. Even a small regiment of cavalry can route many times their own number if they are committed against a foe that is already in a hard fought engagement. A unit that is unprepared or not expecting or able to ready themselves to receive cavalry can be decimated. To take Albuera as an example French cavalry flanked several battalions of British infantry and just demolished them and swept them from the field. Cavalry, regardless of type can swing an engagement or turn a withdrawal into a full on route and inflict tremendous casualties on a disorganised enemy.

An infantry charge can break an enemy unit but only cavalry posses the speed to run them down and truly shatter a unit. Whether that unit was near broken when they attacked or the shock of their charge broke a unit by themselves.

Another interesting side note is that cavalry can force infantry into square simply by their presence. No self respecting infantry commander would let their battalion be caught by cavalry in line. Unfortunately such a formation was far more vulnerable to artillery and small arms fire. Allowing them to be pinned and annihilated by fire that they can do nought about for fear of being overrun by the nearby cavalry.