Leonard,
No, fighting irregular warfare does not lead to gentlemanly behavior, but Jennison and Lane obviously didn't care about gentlemanly behavior. Incidentally Jennison and Lane started this behavior before, what came to be Quantrill's band, existed and therefore came to be the consequences. You are also correct that some Union members fought more gentlemanly than others as did some guerrilla/bushwhackers/Partisan Rangers or what you will. In fact, one cannot say anything about the ~bushwhackers~ that cannot be said to be equally true of the Redlegs and Jayhawkers. It seems to me that to say otherwise is to be in Denial. I hear people whining about massacres and cold blooded murder, yet they always seem to be referring to the ~other side~ and in denial of their group of people, and frankly, I sick of it! It seems to if that if they can't deal with the facts then they should not be in this ~History~ message base. If one alters or denies the facts then it's not History is it?
Lets not forget that there were many blacks that fought for the south too, understand it or not... Personally, I like to think that they saw what was actually going on and chose the lesser of two evils. There is much more to say, but that requires an open mind and personal research, not the mindless repetition of so and so said or wrote in some esoteric book before getting to the Truth.

Don