There is a table at the site that gives the range and muzzle velocity of Artillery of the time. The muzzle velocities for most of these artillery pieces are around the same as a modern .22 caliber rifle! I shutter to think of the soldiers terror when their ranks were hit with grape shot or solid shot traveling at over 1000fps... Let alone charge into it!

http://en.wikipedia.org/wiki/Field_artillery_in_the_American_Civil_War