I had been in the SCA for many years and was proud of my kit and my impression's).  Several years ago I joined a very authentically minded Civil War reenactment unit called the Critter Company.  Now that I am doing a bit more SCA stuff than before, my attitude and thoughts about my impression and kit has changed.  A concept adopted by most authentically minded Civil War units is the BIRD principle.  The BIRD principle is used to explain why some Civil War units go to extremes in their kit (down to stitch count, authentic dyes, etc.).  The BIRD principle is simply stated "Because Its Right Dammit."  It is a principle which means that you strive to make your kit as authentic as possible - even down to the details. 

In my quest to research and build my kit, I have come across many good sources of documentation and many good vendors.  I have listed a few of these under the links section of this page.

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(Father)...Now if your comrades are planning to go from the king’s apartments to some drinking bout or other merry-making, and you, too, have the king’s permission to seek diversion, you should prefer the forms of amusement which I shall point out to you.  If you are sojourning where horses may be ridden and you have your own horse, train yourself in the art of sitting on horseback in the firmest and most handsome manner.  Train yourself to press the foot firmly into the stirrup; keep your leg stiff and the heel a little lower than the toes, except when you have to guard against thrusts from the front; and practice sitting firmly with the thighs pressed close.  Cover your breast and limbs carefully with a curved shield.  Train your left hand to grasp firmly the bridle and the grip of the shield, and your right hand to direct the spear-thrust so that all your bodily strength will support it.  Train your good steer to veer about when in full gallop; keep him clean and in good condition; keep him shod firmly and well, and provide him with a strong and handsome harness. 

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Father: The man who is to fight on horseback needs to make sure, as we have already stated, that he is thoroughly trained in all the arts of mounted warfare.  For his horse he will need to provide this equipment: he must keep him carefully and firmly shod; he must also make sure that the saddle is strong, made with high bows, and provided with strong girths (1) and other saddle-gear, including a durable surcingle across the middle and a breast strap in front (2).  The horse should be protected in such a way both in front of the saddle and behind it that he will not be exposed to weapons, spear thrust or stroke, or any other form of attack.  He should also should have a good shabrack (3) made like a gambison of soft and thoroughly blackened (4) linen cloth, for this is good protection against all kinds of weapons.  It may be decorated as one likes, and over the shabrack there should be a good harness of mail.  With this equipment every part of the horse should be covered, head, lions, breast, belly, and the entire beast, so that no man, even if on foot, shall be able to reach him with deadly weapons.  The horse should have a strong bridle, one that can be gripped firmly and used to rein him in or throw him when necessary.  Over the bridle and about the entire head of the horse and around the neck back to the saddle, there should be a harness made like a gambison of firm linen cloth, so that no man shall be able to take away the bridle or the horse by stealth. (5)

            The rider himself should be equipped in this wise: he should wear good soft breeches made of soft and thoroughly blackened linen cloth, which should reach up to the belt; outside of these, good mail hose which should come up high enough to be girded on with a double strap; over these he must have good trousers made of linen cloth of the sort that I have already described; finally, over these he should have good kneepieces made of thick iron and rivets and hard as steel.  Above and next to the body he should wear a soft gambison, which need not come lower than to the middle of the thigh.  Over this he must have strong breastplate made of good iron covering the body from the nipples to the trousers belt; outside this, a well-made hauberk and over the hauberk a firm gambison made in the manner which I have already described but without sleeves.  He must have a dirk and two swords, one girded on and another hanging from the pommel of the saddle.  On his head he must have a dependable helmet made of good steel and provided with a visor.  He must also have a strong, thick shield fastened to a durable shoulder belt and, in addition, a good sharp spear with a firm shaft and pointed with fine steel.  Now it seems needless to speak further about the equipment of men who fight on horseback; there are, however, other weapons which a mounted warrior may use, if he wishes; among these are the horn bow and the weaker crossbow, which a man can easily draw even when on horseback, and certain other weapons, too, if he should want them. 

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1. Notice the plurality here (girths).   This is reinforced by period illustrations.

2. Surcingle's are clearly illustrated as well as breast straps.  These were usually just a wide leather belt that wrapped from the front of the horse to the back of the saddle.

3.  Shabrack is a fancy saddle blanket.  May have been decorated.

4.  Blackened - The current school of thought on this is that there is a process that you can expose linen to break it down a bit where it becomes softer.  It includes almost letting the fabric rot a bit.  It will turn darker but apparently becomes much softer.

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