Smoke screens used in combat

I was watching a documentary that showed US troops landing on occupied beaches in the South Pacific during WWII. In at least some of those landings you can see planes flying low and laying down a thick layer of (what appears to be white) ‘smoke’ to apparently hide the extent of the assault from enemy soldiers defending the island.

Does anyone know how they generated this smoke, what it was made of, and whether is was effective? Wouldn’t the smoke also impair the view of the Allied ships and planes trying to soften up the areas around the beaches?

The “smoke” was most likely diesel fuel sprayed onto a hot exhaust pipe. It wouldn’t hamper shore bombardment, because the ships already knew where everything was, and they wouldn’t be shelling while the landings were going on anyway. The smoke was never thick enough to impair aerial attacks. It was only meant to interfere with enemy artillery observers. Possibly this stuff.

I don’t know what footage you were watching. But planes can fly high enough to peak over (and tell the ships where their shells are landing.

Also, the shelling doesn’t necessarally have to high accuracy. It does it’s job if it keeps the enemy hunkered down in their holes instead of shooting at the landing forces.

Presumably they would try to just deploy the smoke screen in such a way to screen their own troops only, or possibly an avenue of imminent assault, so that isn’t an area that needs to be bombarded by friendlies. But smoke doesn’t always go where you want it to.