The Knapsack.

The knapsack has two shoulder straps & is worn squarely on the back. Single strap bags have a tendency to move position, but the knapsack sits pretty firm in one place, especially if equipped with a chest strap as this one of mine is.
My blanket roll is tied to the top of the shoulder straps, my oilcloth is secured under the flap closure along with my market wallet. Spare moccasins are tied to my blanket roll.
This one I converted from a haversack, like many originals were.