What are sappers, they sound cool
Special classes you can get after Soldaat der 2e Klasse, given to the most skilled people in the regiment.
Sappeur(Sapper in english) historicly was an engineer for quick tasks on the battlefield like barricades, which indeed weren't constructed by throwing a hammer.. But as they had a massive epic axe to cut trees(I think to cut trees) we give these ranks to people which are expert in melee.
For Flanquers, most dutch battalions had a few fusilier companies and one flanquer company, which practicly is a fusilier company trained more strategicly in which way they gave a lot of fire support and defending flanks while the rest of the fusiliers could just keep their task, shooting the enemy.. But as we use Sappeur for melee, we will use this one for the best marksman around.
Both these and Soldaat der 1e Klasse can be given after Soldaat der 2e Klasse, so they are practicly equal to eachother though flanquer and sappeur do mean you are rewarded for skill, while Soldaat 1e Klasse is just for discipline(ofc the other 2 need discipline aswell) and activity.
As we are still small we will not give much use to these ranks, though when we grow we will form a small flanquer and sappeur company.
Ofcourse all the ranks are some sort of reward rank, but for these and officer ranks you need to have that little special the average person doesn't have.
I hope this explains enough!