Supporting fire, covering fire, indirect fire, war isn't just about running guns. There are different aspects, artillery being one of the oldest and most effective. Artillery requires a knowledge of math, calculating distance to target, flight path, wind, velocity, momentum,range of explosion (blast radius) etc.No infantry unit can effectively engage without covering fire from an artillery battery, likewise no army can advance on a beachhead without artillery support from a navy.
Artillery is one of the first aspects that go into warfare, and the last to pull out.
"God fights on the side with the best artillery." - Napoleon, Marshal of France
