The final level of each country the Scotsmen visit has a boss character they have to defeat, in order to progress to the next country. Boss characters enter the level at the beginning of the final assault phase (which occurs shortly after the player finishes constructing the haggis factory). Bosses have much higher stats than regular enemies, so eliminating them should be the player's main priority.
For France, the boss is Napoleon Bonaparte. His revolver is virtually one-shot-kill, making him deadly against Scotsmen who aren't in cover. He can fire a lot further than a Scotsman can throw, so the player will have to either use long ranged towers such as the golf clubs or haggis catapult, or move their Scotsmen forward to attack him. He is less effective in melee, fighting with a sword, but because of his deadly ranged attack, it would be ill-advised to charge out into the open to engage him in melee.