When you talk of solid shot and cannister effectiveness you must differentiate between smooth bore guns and rifled guns. The pattern of cannister from a rifled piece has a larger dispersal pattern and is less effective than cannister from a smoothbore.

One post below stated that solid shot was the most prevelant projectile used. I would like to disagree with this. For smooth bore guns (12 pounders)solid shot are recovered in numbers but case shot seems to be the most prevelant type of ammunition used based on schrapnel and whole shot recoveries. Solid round shot was used on columns of massed troops at a distance or to knock down a target such as a fortification or dismount other artillery pieces. Solid bolts from rifled guns are very seldom recovered. As stated previously, round solid shot would bounce along the ground and dismember any soldier who got in the way. It was especially deadly on massed marching columns if the gun could send the shot down the column or in flank on a charging line.

The use of cannister was not as common as the use of other,longer range ammunition. This is simply because of the nature of the battles. However there were many period accounts from those on the receiving end of cannister to attest to it's effectiveness.