I suspect you're right about the fluid versus solid thing, Marc. One of the things you learn from history if you study it properly (trying to understand causes and perspectives as opposed to block memorization of dates... ) is that most events are very fluid. Based on this, I think of CoGs as shifting targets and areas of importance. By way of illustration, during one phase of a conflict a CoG may be a country's logistics hubs, while at another phase it could well become their power grid, information systems, or ethnic/cultural differences. One could argue that in the US Indian Wars two vital CoGs were the buffalo for the Plains Indians and a variety of tribal differences among the Apache. Two different "theaters of war," if you will, with two different CoGs, but the same overall campaign. There were others within each conflict, including tribal differences among the various Plains Indians (the different relationships with the Whites held by the Sioux peoples as compared to the Crow, for example), showing that there can in fact be multiple CoGs within a single conflict, and that each in turn can be examined and targeted. Wise commanders understand this, while others look for the lockstep answer.