To strafe is to attack from above with bullets or bombs. During World War I, planes fitted with machine guns flew low so they could strafe targets below.
Think of a quick-firing machine gun or rapid series of bombs to understand the military verb strafe. This technique made it possible to mount deadly attacks on the enemy, provided that planes could fly at very low altitudes. Technology improvements by World War II meant that pilots of these planes were better protected in cockpits. The word strafe comes from a German catchphrase used during World War I, Gott strafe England, "may God punish England."