A civil war is simply a contest over the rightful owner of sovereignty, and we can look at sovereignty as the right to hold the monopoly of power, usually the right to kill. I say usually because this is not the place for a long digression on the US constitution and the right to bear arms, suffice to say that it is the only the states who are able to lawfully execute people
Uprising, insurgency or guerrilla campaigns may fail on a number of grounds, right authority and likelihood of success in particular, but also on tactics applying proportionality and military targets.