It was largely self serving, at least in terms of the motives for the monarchy, and they paid dearly in the end. Not only did they nearly go bankrupt supporting the war, but their own people were inspired to overthrow their monarchy in part because of what they witnessed from us.

I haven't watched more than the first season of Turn and it has been a while, but one of my favorite characters from the revolutionary war is a frenchman, Gilbert du Motier, Marquis de Lafayette.