This sequel to the award-winning Crown of Glory takes Napoleonic Grand Strategy to a whole new level. This represents a complete overhaul of the original release, including countless improvements and innovations ranging from detailed Naval combat and brigade-level Land combat to an improved AI, unit upgrades, a more detailed Strategic Map and a new simplified Economy option. More historical AND more fun than the original!
I think this is an old COG rule that was superseded by the scale (i.e. division / brigade) modifiers. Just ignore that line in the manual. When you play at division level, artillery get +50% bonus, other units +100%; there should be a line in the report for this.
They are just scale modifiers -- to represent the fact that division combat turns are proportionally longer than brigade level. I'm not sure there is any place that discusses them in detail.