Enfilade and defilade are concepts in military tactics used to describe a military formation's exposure to enemy fire. A formation or position is "in enfilade" if weapon fire can be directed along its longest axis. A unit or position is "in defilade" if it uses natural or artificial obstacles to shield or conceal itself from enfilade and hostile fire. The strategies, named by the English during the Hundred Years' War, use the French enfiler ("to put on a string or sling") and défiler ("to slip away or off") spoken by English nobility of the time.
Enfilade fire—gunfire directed against an enfiladed formation or position—is also commonly known as "flanking fire". Raking fire is the equivalent term in naval warfare. Strafing, firing on targets from a flying platform, is often done with enfilade fire. It is a very advantageous, and much sought for, position for the attacking force.