You're probably thinking of Medieval Venice. Also the Byzantine Empire, at least post-1000 AD. I believe (if memory serves) that both Venice and Byzantium depended on unreliable foreign mercenaries -- to their misfortune.
But I don't think that the analogy applies here, as Letters of Marque and Reprisal approve the armament and Bounty-payment of the US's own citizenry. That's an entirely different matter. Mercenaries, yes, but of the home-grown variety. They live here. Their homeland is the same country -- the US of A -- for which they fight, and from which they collect Bounty.
A domestic armed citizenry? I consider that a good thing. In fact, I bet you do too.