Fire and movement or fire and manoeuvre is a military tactic that uses suppressive fire, or threat thereof, to decrease the enemy's ability to return fire, organization and unit cohesion, and morale. The tactic is used by small unit commanders on the modern battlefield. The "movement" part of the action consists of a separate organizational unit moving forward in greater safety afforded by the suppressive fire laid down on the enemy. The tactic is often assigned to the Swedish warlord and King Gustavus Adolfus as he probably was the first to use the tactic in wartime. This he did in the Thirty Years' War against his Catholic opponents.
Fire and movement can be performed by units of whatever size appropriate: by as few as two soldiers up to companies or larger. It works when a military unit suppresses the enemy with an appropriate level of fire, while at the same time, another military unit advances. After a short time, the advancing unit will halt and begin suppressing, allowing the previously suppressing unit to advance to a new position and begin the cycle again. Enemy suppression can also be achieved with direct and/or indirect fire from combat support units. Artillery, mortars and armor are a few examples of combat support units often used in fire and movement.
In the United States Military, a basic fire and movement tactic is called overwatch. There also exists several variations of overwatch, generally adding further description to more accurately describe the specific maneuver.
A unit fires upon an enemy to distract or suppress them allowing another unit to assault, flank or encircle the enemy. The enemy will be pinned down and can not react, and will be
forced to take cover until the flanking unit engages them.
Heavy and continuous suppression fire keeps an opponent suppressed and therefore limits the overall firepower of a unit (if a platoon has 30 soldiers, but only 15 are shooting back because the other 15 are being suppressed, that unit's firepower has been reduced by 50%). The fire cuts down on an enemy's intelligence in that they are not able to assess the situation clearly.
While a base of fire is set up, the second unit will advance to cover in front, in the process setting up a new base of fire at this point. After a new base of fire has been set up, the first unit will advance, under cover of the new fire base, to a new position and set up another base of fire.
These actions are repeated until the units have closed upon the enemy position. At this point a unit will close in on the enemy and destroy them, often by throwing grenades, close-quarters battle techniques, and hand-to-hand combat.