I will have to agree with Geo on this concerning the battles fought between the the Army of Northern Virginia and the Army of the Potomac. When you travel west the difference in casualties gets a lot closer. If you study the official records and Battles and Leaders where casualties are listed, casualties are broken down only by regiment and not brigade, you can see the difference and you have to conclude that the Southern regiments consistantly shot to pieces the Northern regiments, regardless of whether they were strictly defensive or offensive actions.