These British military leggings seem very much like the ones used by civilians or NAs. Captain John Knox, Historical Journal, 1757. He was with the 43rd Regiment of Foot at that time.
"The Colonel is ordered to provide the regiment with flannel under-waistcoats, and Leggers, or Indian stockings-, here follows a description of them: Leggers, Leggins, or Indian spatterdashes, are usually made of frize or other coarse woolen cloth; they should be at least three quarters of a yard in length; each Leggin about three quarters wide (which is 3 x 3) then double it, and sew it together from end to end, within four, five or six inches of the outside selvages, fitting this long, narrow bag to the shape of the leg; the flaps to be on the outside, which serve to wrap over the skin, or forepart of the leg, tied round under the knee, and above the ankle, with garters of the same colour; by which the legs are preserved from many fatal accidents, that may happen by briars, Humps of trees, or under-wood, &c, in marching through a close, woody country; the Army have made an ingenious addition to them, by putting a tongue, or sloped piece before, as there is in the lower part of a spatterdash, and a strap fixed to it under the heart of the foot, which fastens under the outside ancle with a button. By these improvements they cover part of the instep under the shoe-buckle and the quarters all round; the Indians generally ornament the flaps with beads of various colours, as they do their Moggosan, or slipper; for my part, I think them clumsy, and not at all military; yet I confess they are highly necessary in North America; nevertheless, if they were made without the flap and to button the outside of the leg, in like manner as a spatterdash they would answer full as well: but this is a matter of opinion."
Spence