As long as we're talking about tech, an 18th century level of firearms technology and production would mean that full plate had been phased out, most swords and pole arms were gone; we'd passed the medieval combat you associate with sword and sorcery by literally centuries.

Most combat was done via rows of riflemen, firing in succession, then taking land by charging with their bayonets. Officers would receive cavalry, and there'd also be teams for cannons.

Also there's no reason to use magic with this level of gun technology. Why would you try and cast a weak fireball that might kill you when you could just shoot a gun that won't kill you?
Why would you bother using magic at all when it would probably kill you if you do anything wizards are normally useful for?