You want a happy country that is disproportionately powerful for its miniscule size?
If you didn't ask for it in Europe, my first thought would have been "Sorry, it's in OTL and called Singapore." But since you said Europe, my first thought was, "Sorry, it's in OTL, and it's called Luxembourg."
Now this is serious. IIRC, every Luxembourgian male between 16 and 60 is legally a military reserve. (The gov't can call them up.) (Or is that Liechtenstein? I can never remember which of the two that is.) Luxembourg is also home to the rregistration for every purely NATO aircraft, including 17 E-3 Sentry AWACS planes. And if someone attacks Luxembourg, the entire might of the Western world comes down on them without Luxembourg having to lift a finger. THAT is power.