CAMP PENDLETON, California — If thousands of Marines are off a hostile shore, it's typically an exercise in futility for the enemy to stick around and wait for the assault.

On Thursday, US Marines with the 15th Marine Expeditionary Unit embarked on a training exercise, carrying out an amphibious assault on a town littered with notional insurgents — and as should be expected from a premier maritime force, the grunts dominated.

Business Insider was on hand to watch as Marines left their ship, the USS San Diego, and headed onshore, practicing landing on and taking over an enemy beach.

Here's what we saw.