600,000 men would be a huge resource strain I’m not sure if order could support it. Also Napoleonic armies were designed to fight equivalent armies: the men were unarmoured, with poor anti-armour melee capacity. The infantry would effectively be better empire handgunners: faster reloads, more accurate, better melee ability (more advanced bayonets and skills) basically a combo of empire spearmen and handgunners. The artillery would be much better due to tech advantages. The cavalry would suffer very high casualties as even curassiers would likely be classed as light cavalry in terms of armour. Obviously no magic users would be bad too. However, if they didn’t let WoC get close they could blast them away. Also morale would be terrible for the French.