Flag me if you find it please.
First the good news. Found the article (tribesman, barbarian, citizen) in one of my many anthologies: Imperial Stars Volume 1: The Stars At War, also found the original source listed online: Analog magazine, May 1961.
Now the bad news. It ain't transcribed. It's a two parter consisting of about sixteen pages. If I can find time, I will type and post the article.
In the meantime, I leave you with this snippet...
The barbarian's inevitable and highly suicidal error is to think that, because the citizen obviously hates fighting, the citizen must be unable to fight well.
The fully developed Citizen actually seems to be every bit as hard-headed, ruthless, and dangerous a fighter as any barbarian—he just uses his ruthless determination wisely instead of egocentrically.