Marines like to get the first blow in and disorient the enemy by introducing some form of deception into every major mission.
"Marines want to leave the enemy as disoriented as possible. To do so, they not only strike first but also try repeatedly to hit the enemy at times, in places, and in ways that the enemy is least likely to have anticipated.
As part of this effort, the Marines try to work some form of deception into every major mission. During the Gulf War, according to Zilmer, the Marines sent a small force arranged to look like the tip of a larger one speeding into Kuwait, drawing the Iraqi's artillery fire. The fire allowed the allied forces to pin down the location of the enemy artillery units and destroy them. Meanwhile, the Marines' main force was speeding into Kuwait along an entirely different path.
The focus on leveraging attacks to have maximum psychological impact is a critical one for the Marines, and it's one of the hearts of maneuver warfare. A demoralized opponent is unlikely to fight well, no matter what its advantages."
Source: Marines Corps Business - Principle 23 Surprise and disorient the opposition