Canon balls in wars of the 1700s and 1800s until shells were invented.

During this era, there were basically three types of ammunition fired by field artillery against enemy troops on the battlefield.

Round shot, case (canister) shot and grape shot.

Round shot was basically a round ball of wrought iron (although stone was not uncommon in earlier eras) that was fired at a flat trajectory with the intention for the ball to skip or bounce and hopefully plow through multiple ranks of enemy troops before it lost enough energy to no longer cause harm. This was of course easier if the ground was hard and dry and harder if it was soft, wet or otherwise not suitable. Napoleon did delay his attack at Waterloo 3-4 hours during the morning of the 18th of June 1815 to allow the ground to dry up after heavy rains during the night, partially because he wanted to be able to use his artillery better. While unhistorical in many ways, the movie 'The Patriot' have a good scene that shows how a cannonball would skip or bounce over the battlefield. This ammunition would have the longest range.

Case (or canister) shot was a pre-decessor to the shell. It consisted of a thin casing in which musketball sized iron or lead balls were contained. These balls could be attacked to a rod of iron or led. The gun woudl fire the case and it would crack from the strain a short while after leaving the barrel, spreading the balls in a cone-shaped pattern to the front. Early case shots could be made from wood, but later were almost always made from thin sheets of iron. There were improvised case shots, filled with stone shards, discarded nails, jagged iron pieces (collected from destroyed guns, enemy case shot leftovers or just leftovers from smithing and casting metal) and other things. Towards the end of the era, the case shot often included a small charge of gunpowder ignited by a fuse to ensure that the shot was well-distributed over a large area and cracked in the air, showering enemy troops from above with the shrapnel. Unlike modern shells, the case shot did not have a lot of explosives and would not be able to 'dig out' or destroy a field fortification like an earthwork or trench like a modern high-explosive shell would. It is very likely that Swedish King Karl XII was killed by an iron ball from a Dano-Norwegian case shot fired from Overberget as he inspected the siege trench construction against Halden 1718. This type of ammunition would be used at medium range.

Grape shot was basically turning the cannon into a giant shotgun. Iron or lead balls the size of musket balls or grapes (thus the name) either attached to a rod or loose, would be loaded into the cannon and fired at very close ranges against enemy troops closing in on the cannon. Earlier or improvised grape shot could be the same kind of leftovers or junk as in the case shot, or even gravel. Deadly effective, but with very short range - if you were using grape shot, the enemy was usually within the range of their own muskets, and the crews of the cannons stood at risk of receiving return fire from very angry enemies who knew very well how deadly the cannon could be to them if they allowed it to fire again.

Other ammunition used during this era were shells - not like modern shells, but rather hollow balls with timed fuses fired by mortars and howitzers, often against enemy fortifications to shower the defending troops with shrapnel from above, against which the walls were ineffective as protection. During the 1840s, such shells became available for cannons as well.

Cannons used for coastal defence, often in forts protecting harbours and important straights could make use of forges to heat cannonballs to the point of glowing, in an attempt to set attacking enemey wooden ships on fire.

Speaking of ships, half-balls connected by rods or chains were used at sea - the intention was for these to rotate and thus cover a larger area and be able to destroy the rigging (sails and ropes) of the enemy ship, leaving it dead in the water and helpless.