The LINE (Linear Infighting Neurological Override Engagement) Combat System was a martial arts program used by the United States Marine Corps between 1980 and 2002.

Designed to be performed even while wearing full combat gear (including flak vest and pack), LINE focuses on causing the most painful damage possible with the least amount of movement.

The accurate use of pressure points and efficient breaking of bones and hard tissue (especially the elbows, wrists, knees, and nose) are among the first steps of every move. This is intended to cause a "neurological override": such extreme pain that the opponent's brain can not sufficiently focus to allow him to fight back and may even cause the opponent to lose consciousness.

The initial attack is followed by a takedown, with the attacker generally staying in contact with the broken limb to maintain leverage on the target.

The takedown is immediately followed by a straight-legged downward stomp of the opponent's head with the heel. As LINE is used while wearing combat boots and full gear, the impact is intended to be fatal. This being said, it should be kept in mind that even blunt force of this weight on the head of a healthy adult is unlikely to kill immediately.

Advanced LINE training teaches the most anatomically economical uses of knives, bayonets, and improvised weapons such as e-tools and helmets.

LINE was replaced in 2002 by the Marine Corps Martial Arts Program (MCMAP).