Think about how hot that is for a moment. Now imagine having to do heavy physical activity in it, moving large equipment, carrying 80 pounds of gear, hiking everywhere, etc... Your odds of developing heat stroke are extremely high.

Having a cool place to relax and recover in is absolutely necessary. Otherwise, plenty of soldiers would be suffering and/or dying. The overall shape of the military stationed there would decline, and would lose that advantage over their enemy.

They also build their permanent structures in a way that maximizes airflow and cools the building. There was a NYT article a few years ago about an 800 year old, un-air conditioned mosque in Baghdad where the temperature was in the low 70's year round.

Pre air-conditioning, western buildings had features like this as well.

Speaking of the south, many many buildings in Greece and Italy have a simple mirror and a steel tank on their roofs to supply hot water. No electricity or sophistication needed.

Even in the cold north, simple radiators provide enough heat to keep a house warm. Thick walls and small windows are enough to contain air temperatures in both cold Finland and hot Greece.

I think this is called "heat recovery ventilation" in English.

I cannot speak for current operations - in the 90s we did not use A/C for the tents we lived in, but for the tents the computers were in. They also functioned as dust filters.

What about the Gobi desert?

Unfortunately, I can't really answer for the Bedouin.

Overall, this sounds like another point for thick, heavy tents (or in terms of the urban jungle: thick brick walls here in Europe keep wonderfully cool in summer and warm in winter.)

But I can also see how the a/c is probably one thing they do for keeping morale up... so this might not only be a thermic/physical problem.