Infantry combat is "young man's work"

That's the damn truth. Found a link to this at Q and O, and it reminded me of something. In the article Mr. Smith notes:
So, a 5’11’’ Marine weighing 175-180 lbs., weighs about 250-280 lbs. in full battle kit. Yet with this added weight, he must remain strong, fast, agile, able to withstand long road marches in extreme temperatures and capable of fighting another man of equal size and weight in the often-close quarters of an urban environment.

That brought to mind a passage I posted once before, taken from David Drake's book Fortress:

The thing that nobody who directed war movies understood- and why should they? It would come as news to rear echelons in all the various armies as well- was that the guys at the sharp end carried it all on their backs.

The irreducible minimum for life in a combat zone was water, arms and munitions, and food. In most environments, heavy clothing or shelter had to be factored in as well; exposure in a hilltop trench would kill you just as dead as a bullet.

Helicopters were fine, but they weren't going to land while you lay baking on a bare hillside traversed by enemy guns; so you carried water in gallons, not quarts, and it was life itself. If you ran out of ammo, they'd cut you apart with split bamboo if that was what they had... so you carried extra bandoliers and extra grenades, and a pistol of your own because the rifle you were issued was going to jam at the worst possible time, no matter who designed it or how hard you tried to keep it clean.

Besides that, you carried a belt of ammo for one o f the overburdened machinegunners or a trio of shells for the poor bastard with the mortar tube on his back. You were all in it together; and besides, when the shit hit the fan you were going to need heavy-weapons support.

And the chances were that, if you were really trying to get the jump on the elusive other side, you had a case of rations to hump with you as well. Ever time a resupply bird whop-whopped to you across hostile terrain, it fingered you for the enemy and guaranteed that engagement would be on the enemy's terms.

So you didn't move very fast, but you moved, and you did your job of kicking butt while folks in strack uniforms crayoned little boxes and arrows on acetate-covered maps, learnedly discussing your location. That was the way the world worked; and that was why Tom Kelly felt subconsciously better for the equipment slung on his body as he shuffled into combat."