[DugwayDuke]

Smoke screens are not illegal. The issue is with this portion:

"...as a potent psychological weapon against the insurgents in trench lines and spider holes when we could not get effects on them with HE (high explosive)" munitions."

When a WP 'explodes' it fragments into small pieces that fall to the ground. I think the author was saying these small pieces would fall into the trenches and spider holes. Please note, I'm not criticizing the use of WP as an anti-personnel weapon. In fact, I'm all in favor of it. Never understood why it's ok to blow a guy up or shoot him full of holes or bayoneting him but burning him is somehow wrong.

[R. Scott]

Never understood why it's ok to blow a guy up or shoot him full of holes or bayoneting him but burning him is somehow wrong.

And – the bayonet can only be used to stab, not slash. It’s against the convention to have a sharp edged blade.
Strange how much time we spent sharpening our bayonet blades.