Additionally, as has been pointed out on this forum before, soldiers used to also be much smaller built than modern US and Brit ones. They used to be fairly small and lean. Now most are muscle men, 5'6" to 6'+. This is also primarily a recent (latter 20th Century) thing.

Imagine all the soldiers (as they used to be built) carrying all that stuff. Yet, that is what they were used too, especially compared to today (with modern motorized -and rotored- rapid resupply.