Campaign is usually a push or series of battles by one side versus another. In Take Command War, there has been currently 3 campaigns:

Border Line Campaign-February 6-9,1861

Laurel Junction Campaign-February 9-11,1861

Richmond Campaign-February 11-present

A campaign usually consists of 3-15 battles spread in the same area. An example is the Laurel Junction campaign, which consisted of 7 battles around/in Laurel Junction.