As in, how useful was it at taking out enemy soldiers in the 19th century compared to the 17th, 18th and 20th? Did it have a mostly morale effect or was it an actually devastating weapon?
From what I understand, the advent of the quick-firing system was what lead to a massive increase in deadliness, but I also understand that even during the Napoleonic Wars, artillery was quite deadly. I'm guessing it was the development of various types of ammunition that started the evolution of the artillery, with the quick-firing system being the latest and most deadly improvement, so was the combination of ammo and guns the Napoleonic Wars deadly or not?
I'd imagine that artillery of the time was effective, otherwise they would not have fielded it! I think it is a misconception that black powder, muzzle-loading artillery was ineffective on the battlefield. While the rate of fire was lower than breach loading artillery and most engagements were done within line of sight, heavy pieces still had quite a bit of range (far more than small arms like muskets or later rifled muskets), and also maintained a potential to destroy larger pieces of equipment on the battlefield (try taking out a fort's walls with musket fire, for instance).
For a few examples of rifled artillery from the US Civil war see this video -- they are firing live rounds at a burned out APC on a range. Looks effective to me. https://www.youtube.com/watch?v=jL1DkrYL70s
Also, see this video below of the use of canister shot. This would clearly be a bad day for approaching infantry in closed ranks. Please note, however, that canister would only be used at the last moment while solid shot was typically used at a further range as these were moer accurate and could pass through many rows of soldiers. Alternatively, there could also have been the use of air bursting fragmentation rounds...
I think the efficacy of Napoleonic artillery is best demonstrated by some tables and figures from the ever helpful Nafziger. http://puu.sh/loOf9/e884cb196a.png This first image shows the expected rounds fired at certain ranges and the type of ammunition.
http://puu.sh/loOwN/c1f34073cb.png This second table is from the German historian Muller, who served with the KGL, and shows the expected casualties caused by a single 6 pounder being attacked by either cavalry or infantry in line.^1
That he expected a single 6 pounder to cause 138 casualties when defending against infantry is I think indicative of the huge damage that artillery was able to deal out. I have read before, but have been unable to find a citation for, that artillery accounted for over half the casualties on a Napoleonic battlefield, and with the figures suggested by Muller in one 6 pounder defending a single enemy attack this is easy to believe.
