The leg harness covers thigh, knee, shin and foot — cuisse, poleyn, greave and sabaton — over mail or padded hose.
A leg harness is the assembly covering the lower limb: a cuisse over the thigh, a poleyn at the knee, a greave on the shin and calf, and a sabaton over the foot.
Legs were armoured early. A rider's legs hang at exactly the height an infantryman can reach, and a man on foot whose knee or thigh is opened is out of the fight immediately, so the leg is one of the first places plate appears.
It is also the most expensive coverage in stamina. Weight on the leg is lifted with every stride, which is why armoured men fighting on foot tire so much faster than the same men standing still.
The cuisse is a plate shaped to the front of the thigh, strapped round the back and often hung from a belt or from the fauld so its weight is carried at the waist rather than by the leg itself.
The poleyn caps the knee and usually carries a wing on the outer side, guarding the joint's vulnerable outer face. It is joined to the cuisse and greave by short articulating lames so the knee bends fully.
The greave is made in two halves hinged down one side and closed with hooks or straps on the other, enclosing the calf completely. Below it the sabaton is built from overlapping lames, following the foot and flexing as it does.
Mounted, the legs are the most exposed part of the rider. Infantry attack them because they are within reach when nothing else is, and a rider brought down by a leg wound is as beaten as one unhorsed.
On foot, the legs are the target of choice in armoured combat after the gaps. The fifteenth-century manuals include strikes and hooks to the knee and ankle, and the poleaxe's beak was used for exactly that.
The sabaton is a compromise the other pieces are not. Long-pointed sabatons were fashionable and their points were removable, because a knight who dismounted needed to walk and fight rather than pose.
Its strength is complete coverage of a limb that is both exposed and structurally critical. The legs carry the whole harness, and a man whose leg fails is finished regardless of how good his breastplate is.
Its cost is measurable. The 2011 study that put a full harness at roughly double the energy cost of moving unarmoured attributes much of that to leg armour specifically, because it is lifted and swung with every step rather than merely carried.
The joints are the weakness, as always. The back of the knee cannot be plated without stopping it bending, so it is left to mail or padding — and the fight books know it.
Mail chausses — leggings of riveted mail, laced to a belt — are the twelfth- and thirteenth-century solution, and they are as expensive and heavy as a hauberk for a much smaller area.
Plate arrives at the knee first, as poleyns strapped over the mail in the late thirteenth and early fourteenth century, for the same reason plate arrived first at the elbow: the joints are where a blow concentrates.
Through the fourteenth century cuisses, greaves and sabatons follow, and by about 1400 the leg is fully plated with mail surviving only behind the knee. The sixteenth century then begins shedding it, and leg armour is among the first parts of a harness to be abandoned.
Italian legs are smooth and rounded, matching the globose breastplate, and Milanese work is generously proportioned with heavy poleyn wings.
German gothic legs are narrower, fluted and drawn to points, with the long pointed sabaton at its most extreme in the later fifteenth century.
Practice also differs by use. A harness for fighting on foot dispenses with the long sabaton points entirely and often uses a heavier, more enclosed greave.