A short and informative piece, it was also pleasant to learn that others are curious in such minutiae and to confirm that I'd gotten it right in my novel! When I began writing, I remember having the same question: did they have pockets? I kept thinking of Mary Rowlandson (whose captivity narrative I have taught in American Literature classes). She refers to her pocket (in which she keeps food), but it means a sort of exterior pouch, one that would have from her belt.
My own research was helped by the excellent museums I visited along the Hudson (see the road trips and research section of this blog). They had excellent displays on the uniforms and articles of daily life. Though they didn't detail the pocket contents (that I recall), the museum at New Windsor did show what a typical soldier carried in his haversack.
Here's to obscure knowledge and those who enjoy it!