Should you have some time to waste, take a look at a 40-year-old movie called "Platoon" -- very popular in its time, but not a particularly edifying bit of filmed fiction.

It does have one thing in its favour, however: the producers evidently consulted a genuine Nam veteran who told them how soldiers of that time adapted to the jungle heat. All the actors playing grunts wear olive-drab towels under their helmets, with the ends hanging down to screen their necks and faces.

Nowadays, soldiers (from First World armies) in hot countries carry Camelbak water packs. "Piss white, yer all right", said my dear old sergeant. Add that weight to the body armour and the ammo load ... My knees hurt just thinking about it.