Individuals such as Lafayette and his corps of volunteers had to slip out of France to get here and fight. Lafayette adored Washington and the idea behind our Revolution, but refused to take part in the French Revolution (He was, after all, the Marquis De'Lafayette) and almost lost his own head to the mob.
Despite being an aristo, Lafayette was politically untouchable. Having backed American independence, Lafayette found himself a Certified Friend of Liberty, a status that served him well when the jacobin mobs started baying for blood.
Nice to see that, for once, a good deed did go unpunished.