Marshall was also writing about what was, essentially, a conscripted US Army (including penal service), with a very different discipline model slowly starting to phase out, the Army's various "corps" finally being truly integrated into a single service (and with a single unified rank system), a very different tactical deployment model, and a much different understanding of the expendability of troops (and not just by the officers).
Not to mention a vastly different training model, especially for IET (Initial Entry Training - aka Basic and AIT). Sure, there was Basic Training and Infantry Training, but the expectation was that most of the needed skills would be acquired in unit. Modern IET is much more science-based in training techniques, and much more about teaching skills than about instilling strict obedience (but it still is supposed to do that, too), and much more emphasis on physical fitness is present as well.
The average infantryman has considerably better physical fitness now than during the Korean conflict. He's also volunteered, and so generally has better morale. Further, he's been conditioned to carry more, for longer. And, on top of that, his IET is longer.
Plus, the infantry gear is more comfortable than it was. Modern load-bearing gear is actually rather comfortable - comfortable enough that it sells commercially new to sport/recreational hikers and hunters. The footwear and uniforms are also better suited for field use. (Having worn USAF/CAP Fatigues and US Army BDUs both in the late 1980's, the BDUs are FAR more comfortable when doing hard physical activities. In office, I'd rather have the Fatigues. I'm told the ACU and NDU is even more comfortable for field use.)
It's made a difference. Force march distances are still the same, despite more gear, fire for effect is up considerably, and firing at all in any given engagement is now over 90%, and fire during deployment is over 95% for infantry... versus a Korean era 50% and 90%. (You still wind up with a few guys who choke when real bullets start coming their way due to hostile intent.)
Not to mention a vastly different training model, especially for IET (Initial Entry Training - aka Basic and AIT). Sure, there was Basic Training and Infantry Training, but the expectation was that most of the needed skills would be acquired in unit. Modern IET is much more science-based in training techniques, and much more about teaching skills than about instilling strict obedience (but it still is supposed to do that, too), and much more emphasis on physical fitness is present as well.
The average infantryman has considerably better physical fitness now than during the Korean conflict. He's also volunteered, and so generally has better morale. Further, he's been conditioned to carry more, for longer. And, on top of that, his IET is longer.
Plus, the infantry gear is more comfortable than it was. Modern load-bearing gear is actually rather comfortable - comfortable enough that it sells commercially new to sport/recreational hikers and hunters. The footwear and uniforms are also better suited for field use. (Having worn USAF/CAP Fatigues and US Army BDUs both in the late 1980's, the BDUs are FAR more comfortable when doing hard physical activities. In office, I'd rather have the Fatigues. I'm told the ACU and NDU is even more comfortable for field use.)
It's made a difference. Force march distances are still the same, despite more gear, fire for effect is up considerably, and firing at all in any given engagement is now over 90%, and fire during deployment is over 95% for infantry... versus a Korean era 50% and 90%. (You still wind up with a few guys who choke when real bullets start coming their way due to hostile intent.)