What does "infrastructure " in this passage refer to?

Suffice to say, it wasn’t. The war dragged on for another four years. The infrastructure of the various militaries involved, especially the French, German, and English, were woefully under-equipped to deal with the new weaponry and warfare style that became popular during this period: Trench warfare, to the point where it became known as the “War of the Trenches” or the “Trench War.”
https://www.animefeminist.com/history-not-with-...

@ttmto ok so,

... the various militaries involved were ... woefully under-equipped:

This means the military do not have the necessary equipment to operate properly, this would include weapons, bullets, vehicles, etc.

What this implies is that they do not have enough raw materials to build/make this equipment.

On the other hand, the original sentence says the military infrastructure is under-equipped, meaning that the machines used to make the weapons, bullets, etc are not good/not working properly or that roads/railways are not wide enough/not strong enough to handle the weight of tanks.

In other words, military under-equipped means the soldiers do not have enough equipment, while the latter means there is enough equipment, but the equipment cannot reach the soldiers due to bad transport, etc.

From the context, the latter is appropriate as trench warfare meant that the war became one of attrition. Thus, there was a lot of stress placed on transport such as trains/roads to get equipment to the soldiers. Also “new weaponry” could refer to tanks, which were too heavy for roads and too big to put on trains, meaning the infrastructure is under-equipped, not the military per se.