Mystara (OD&D) works like this. I ran a Thyatian (fighter-dominated) invasion of Alphatia (Wizard-dominated). One small battle featured an assault by Thyatian infantry against a position held by Alphatian boltmen - low-level mages armed with wands of lightning bolts. The Thyatians spread out their force so one bolt only killed one man, and were able to get into melee with heavy-but-acceptable losses and slaughter the Alphatian mages. Of course the Thyatians in this battle started with around 10:1 numerical superiority. Of course wands of fireball would have been a lot deadlier; for some setting-specific reason they weren't as common. Maybe the Alphatians had discovered how to make lightning bolt wands particularly cheaply.
Assuming level-distribution is similar and both sides can access minor magics, a wizard-based force won't dominate a fighter-based force IMO. Wizards are very vulnerable until they get 3rd level spells (especially Fly). 12th level Wizards can do huge damage, but are often easily killed by a 12th level fighter with a couple of potions (or spells cast on him) to enable him to detect & reach his doubtless invisible & flying opponent.
