Military force mounted on horseback, formerly an important element in the armies of all major powers. When used in combination with other military forces, its main duties included gathering information about the enemy, screening movements of its own army, pursuing a defeated enemy, striking suddenly at detected weak points, turning exposed flanks, and exploiting a penetration or breakthrough. In the late 19th century, largely because of the introduction of repeating rifles and machine guns, cavalry lost much of its former value. By World War I, a cavalry charge against a line of entrenched troops with rapid-firing small arms was suicidal. Armoured vehicles soon replaced horses, and by the 1950s no modern army had horse-mounted units. Today's units designated cavalry employ helicopters and light armoured vehicles in ways analogous to horse cavalry.