“Man has been carrying stuff on his back forever. A backpack is nothing new.” Nena Kelty
Early WWII the U.S. Army developed and adopted its first rucksack during in 1941. It was canvas duck sack/bag mounted on a steel wire or rattan frame. This frame and heavy felt pads on the back and shoulders supported the load to help keep it off the wearer’s back. Three pockets were on the outside of the bag used to store additional gear. Brass snap hooks were used to close the two side pockets and the cover flap. Functional but limited in loading ability.
Resources[Hard Shell UK]