Defilade

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 it from enfilade and hostile fire. The strategies, named by the English during the Hundred Years' War, use the French enfiler and défiler spoken by English nobility of the time.