I can't tell you exact number regarding weight because I'm no military historian but I can't say that they were carrying significantly less gear the modern soldiers do now.

Nowadays soldiers are a little bit more specialized and they currently carry about the same weight as a knight did in a full suit of armor.

But it is silly to say a soldier, because in the military a person has a particular role and not every Soldier needs to carry everything. Plus intelligence was used so they don't need to carry every piece of equipment that they may need when entering a war zone.

So typically all what's the typical US soldier would carry is a main weapon a sidearm a combat knife which is designed to do multiple tasks, a multi-tool sorts, canteen that may contain 1 to 3 days worth of food, but is also capable of being heated. Some matches, maybe entrenching tool if they've determined that you need one, along with some other specialty equipment if you need them. Engineer may come onto the battlefield with a rocket launcher some Dynamite for barbed wire or entrenchments and that may be it when comes to Specialty equipment. A radio operator would work in a team and then we both carry a part of the radio. A medic may carry a small kit but their primary job is to get soldiers back to the medic tent that has all of the important stuff. And so on.

Song majority of your stuff can be carried in a medium sized satchel. Butt referring to how much weight someone may be carrying it was relatively low, unless you were marching, then it could be between 50-100 lbs because you care carrying stuff like tents and cookware.