The bombs land with awesome explosions, the earth trembles, the upcast of craters jets in the air, the troops are shocked by the blast waves, many bleed from noses or perforated ear drums, they are terrorized into apathy or outright panic. But unless the enemy is nearby and ready to advance immediately, the moment passes.
Since infantry is considered the 'Queen of Battle', and artillery the king, I had inscribed my personal banner "Balls for the Queen". Granted, high explosive 150 millimeter shells aren't exactly cannonballs, but hey, why spoil a perfectly good motto?
If two sides start out at equal strength, and are relatively equally damaged, but one side can replenish his artillery, and the other side cannot, then that one side that gets his artillery back has all but won.