I acknowledge the advances in battlefield medicine; but I don’t think they are relevant to the question. In current wars, if the soldier survives the initial injury and makes it to an aid station, no doubt his survival chances are greatly improved over those in previous wars. That is not the issue.
The question is why in WW1 they survived the initial injury, horrific though it was, when it is contended that today they are less likely to do so. (This contention having been put forward by the documentary.)
Further discussion of this amongst a few of us with direct experience with somewhat more recent battlefield injuries suggests that battlefield tactics and practices may be of some relevance.
In WW1 artillery was often used as a barrage over a largeish area. Many of the shells were fitted with contact fuses. Consequently, many would bury themselves some distance into the ground before exploding.
This meant that the blast effect profile of these individual shells was reduced somewhat, and the the kill cone was directed upwards; soldiers very close to the blast would have been killed either by the immediate blast effect or by fast shrapnel within the cone.
However, if he was somewhat distant from the point of impact, he may be struck by a piece of slow shrapnel which had already dissipated a lot of its initial kinetic energy. And this slow shrapnel was responsible for the non fatal gouging type wounds we are talking about.
So it is possible that due to the density of shelling, and the considerations noted above, proportionately more WW1 soldiers were struck by slow shrapnel. Therefore, the proportion receiving, and surviving, these kind of horrific injuries was higher.
On the other hand, our experience in Vietnam was that when used against exposed infantry, it was most common to use air bursts with proximity fuses. Tactically, it was most common that the target infantry was concentrated within a relatively small area, and the barrage was similarly concentrated.
Therefore, the exposed infantry would have received the full explosive force of the shell and shrapnel.
Therefore, they would have received not only blast effects but also fast shredding shrapnel. So they would have received multiple injuries, in addition to the kind of injuries we have been discussing. So, overall, their survival probability would have been low.
All of this is consistent with our observations in the field; we observed very few survivors of a barrage on exposed infantry, and the bodies were pretty severely mutilated.
Similarly, with entrenched infantry, they were usually concentrated within a very small area; most shells were fused to bury themselves before exploding. This resulted in concentrated blast effects within the entrenchments in addition to fast shrapnel; the survival probability of these individuals was not high.
Our observation of entrenched infantry casualties under these conditions was that the bodies suffered fewer shrapnel type injuries; most of the dead were due to blast effects.
Given these considerations, this may explain the contention that fewer people survive the kind of injuries observed during WW1.
It is not that these type of injuries are not being inflicted, but the general context mitigates against survival.