Slitherine

With FOG:A and FOG:R Artillery and shot can fire overhead if on a hill 1MU away from the unit 'below' them. In FOG:N it seems hills only function as a block on LoS. Why can't we fire over head? One good example of use in the period is Borodino...

That is a mystery that is too mysterious for us to know, we must wait for the words of wisdom from the all might deities of "Rules Author".....

There's a brief explanation on p.52.

To help rationalise the rule, think of all the smoke on a real battlefield which isn't depicted on our wargaming table. As players we can see more of the battlefield than gunners on the ground.

As a game mechanic, we don't want to create a firebase effect. Better to have some phases in the game where we bombard the target and then send in the assault, than having it all happening simultaneously.

Not a case of being a fire base rather being historically correct. Artillery was never super accurate and the renaissance period allows it - so why not this period??? The general idea is to support your troops and help demoralize the other team.

Nosworthy says overhead fire was physically possible, but "this was rarely done, since the troops were generally found to react adversely to the shot and shells flying over them." Overhead fire with reasonable safety requires calculation of trajectories based on relative altitudes and accurate knowledge of friendly and enemy positions, which in a field battle as opposed to a siege are fluid and demand not only visibility but confirmed identification of detected bodies of troops as legitimate targets. Optics were rudimentary and identifying friend from foe depended on clear visibility easily obscured by minor irregularties of terrain, rain, fog, ground haze, or even thin smoke. The greatest safety margin would be firing over troops at a lower level, meaning between hills or over a small valley, although in theory the trajectory of fire would allow firing over troops at the same level as well.

Note the rules do allow shooting through enemy skirmishers (I suppose on the theory that the formed units behind can be seen) - no hill is required.

Indeed, most hills were were not ideal positions for artillery - getting them up, getting them down, and delivering effective fire from atop them were challenges. Ideal artillery ground was a level plain to provide no shelter from gun fire and allow ricochet fire, which was both psychologically and physically damaging to opposing troops, or a gentle, even slope. Convex or concave terrain, whether a hillside or relatively level ground, seriously reduced artillery effectiveness in this period, as would other obstructions. In addition, slight movements of the target were a known tactic for greatly reducing the effect on a target of a continuing cannonade.

Would the ammo expenditure be worth it? If the target was worth it, presumably it would be worth organizing a grand battery under capable centralized control to bombard a target.