Light Dragoons are missile cavalry in Empire: Total War.
Light dragoons are mounted skirmishers, riding to a fight then engaging the enemy on foot.
Their horses are for mobility, not for any shock value in battle and are often little better than nags and ponies, rather than decent warhorses. In battle, this is unimportant as light dragoons dismount and form a skirmish line to harass an enemy and screen the main body of their own army.
The main weapon carried is a shortened musket, originally termed a "dragon" or dragoon (like "rifle" the term came to be applied to the man carrying the gun). This is not an accurate weapon, but is no worse than any other smoothbore.
Light dragoons are also useful in suppressing riotous and rebellious civilians. Their horses give them strategic mobility, allowing them to police large areas effectively and come to the aid of the local authorities.
Historically, dragoons lost their role as mounted infantry over the course of the 18th Century, and became another kind of light cavalry, although they retained the name. The officers and men welcomed the change to a role that had a higher social status (and usually better pay rates).
Light Dragoons have slightly inferior melee statistics to regular Dragoons. However, they more than make up for this by their ability to fire while in the saddle and while on the move. As with regular dragoons, light dragoons have the ability to dismount, although this ability is less useful on light dragoons given their usefulness while mounted. However, their mounted and dismounted stamina are calculated separately, so if they're exhausted whilst mounted, they'll be fresh when dismounted (assuming they haven't already fought when dismounted) and vice versa, their horses will also recover stamina whilst dismounted, and the men will recover stamina whilst mounted - meaning if they're exhausted whilst mounted, it may be better to temporarily dismount them to protect their horses whilst they recover.
Like other missile cavalry, Light Dragoons have a height advantage over infantry and can fire over their heads in most circumstances without fearing for friendly fire. This is only true when the dragoons are very close to the infantry; when firing at the edge of their range, for example, friendly casualties are high.
Although Light Dragoons are formidable missile cavalry, they fare rather poorly in melee, and have very poor morale. This makes them poor candidates for prolonged close combat against anything other than skirmishers, mobs, and other light cavalry. Even against light cavalry, Light Dragoons usually lose and take heavy casualties (unless they are able to fire a volley first). Dragoon vs. Dragoon engagements are usually quick and very bloody, owing to the combination of high destructive power, low defense, and low morale.
One of the largest weaknesses of light dragoons are their tendency to cause friendly fire casualties, particularly when used in tandem with other cavalry. Light dragoons work best alone or properly spaced apart from other cavalry.
Overall, Light Dragoons are some of the most potent cavalry in the game. In terms of firepower, they handily beat their non-European counterparts, Pindari Horsemen and Deli Horsemen, as they have 25% more men per regiment and comparable statistics. They are heavily used by the online community.