Key bone to chew on:
The president here was Woodrow Wilson - and he was an idealist, which means that he was a noble soul touched by ignorance (I consider myself to be an idealist also; I feel like this is better than the alternative). I think he genuinely believed it was his responsibility to help people all around the world find democracy.
The US was drawn into World War I in 1917; Haiti was practically forgotten except by the Marines trying to hold onto it.
Another note -
How did we beat the insurgency in Haiti? We found the guy in charge of the insurgency, infiltrated his camp, and assassinated him. Good times. The insurgency was mostly over by 1920, and after a long, protracted withdrawal, the last Marine contingent departed in 1934.
We were there for almost 20 years.
Meaningful Query - How successful is Haiti now?
How useful are historical parallels like this? I don't know. The frequency of history repeating itself does seem to reinforce the idea that we, as a species, don't change much.