How were the american and french revolutions related?

being similar: they are the consequences of the "Lumières" (Enlightenment), with some ideals of constitution, liberty, self government, etc.

The haitian revolution was the result of a long struggle on the part of the slaves in the french colony of st. domingue, but was also propelled by the free mulattoes who had long faced the trials of being denoted as semi-citizens. this revolt was not unique, as there were several rebellions of its kind against the institution of plantation slavery in the caribbean, but the haitian revolution the most successful. this had a great deal to do with the influence of the french revolution, as it to inspire events in haiti. the haitian revolution would go on to serve as a model for those affected by slavery throughout the world.