The Potential of Magic Users in Mass Combat

Wizards, for the most part, are going to refuse to enter the field of mass combat. Their lack of armor, their lack of hit points, their high intelligence, all incline them against going anywhere near the battlefield.

They are loath to waste any of their precious magical resources on what they will undoubtedly see as a "petty squabble" (no matter how important the battle seems to others). They are far too busy with their magic research anyway, and they are close to making profound breakthroughs, so their time is extremely limited, not to be wasted in "foolish brawling" and "primitive head-butting".

A magic user may be persuaded to contribute some magical assistance if an extreme amount of treasure, services, and concessions are offered in exchange. His assistance would extend to preparing a few scrolls or wands, or the granting of some other magical item, and perhaps "monitoring the outcome of battle" using his crystal ball or scrying device.

Nothing short the immanent threat of extermination would get him to bodily enter the battlefield. Even then, he would expect to be stationed in the safest zone, as far from physical danger as possible, as part of the kings personal guard, on hand to render expert consultation and, perhaps, assistance (only if the direst of emergencies should require it, of course).

Certainly, there is ZERO chance of getting him to fight embedded in a combat unit. If anyone attempted to constrain his "arcane and esoteric freedom and liberty" by forcing him onto the battlefield, he would do everything in his power to escape, and would thenceforth devote all his considerable time and cunning towards plotting revenge upon whomever dared order the affront to his autonomy.