During World War II, ground-to-air attacks consisted of rapid-firing small caliber artillery. The shells from these guns were fused to detonate at particular altitudes so that the shrapnel from the shell had the best chance of striking the enemy aircraft. The Surface-to-Air Missile, or SAM, changed all of this. Flying several times the speed of sound, large SAMs could reach all but the highest flying spy planes, and guided by radar or heat-sensitive tracking, SAM missiles chased down the enemy, requiring attackers to respond with chaff or flares to deflect their pursuers.
