From 1915 to 1934, the US Commander ruled the country with a figurehead Haitian as president. For almost 20 years, the Marines kept Haiti more peaceful and prosperous than it had ever been. They wiped out malaria, built a bunch of roads, bridges and other Corps of Engineers trademark boondoggles, and kept the hotheads under control.
But the locals weren't totally happy. For one thing, the white American troops didn't discriminate the way the "Haitian elite" expected. The "elite" was mulatto and spoke French. They considered themselves way superior to the "blacks," the pure-African peasants who spoke Creole and did all the actual work. Naturally, these mulattos expected to collaborate with the foreign whites to keep the blacks down where they belonged, and they were outraged when the Marines made it clear that as far as they could see, everybody in Haiti was just plain black.
This is what they call poetic justice, I guess. It got a lot less poetic, though, when the Marines left in 1934. A creep named Vincent took power, made up a new Constitution naming him King of Everything for Life, and started sleazy dealings with an even bigger creep named Trujillo, who was King for Life in the Dominican Republic, on the east side of the island.
This Trujillo was a classic 1930s fascist. He used more skin lightener than Michael Jackson and decided that he and his fellow Dominicans were Aryans, whereas those dirty Haitians across the border were nothing but a bunch of uncivilized blacks. Which is pretty ridiculous, because every Dominican I ever saw was a lot blacker than most blacks in the US are.
In 1937, just when Hitler was shifting into high gear in Europe, Trujillo decided to have a little holocaust of his own. He ordered the Dominican Army to kill all the Haitians they could catch in the border zone -- they bagged about 20,000. One of the ways they could tell they had Haitians was when they asked people to say "Perejil." If you couldn't trill your "r"s like they taught you in Spanish class, you got the chop. Literally, because Trujillo told his soldiers to use machetes, not rifles. That way he could say it was enraged local peasants who did the killing. And besides, like the English king said in Braveheart, bullets cost money.
Nobody cared about all those dead Haitians. Didn't even notice. They were too worried about what was going on in Europe. (This was back when Europe actually mattered.) And to put it coldbloodedly, nobody ever has cared much what happens to the poor messed-up Haitians anyway. The US demanded that Trujillo pay reparations, which they bargained down to $500,000, which if my calculator is right comes to $25 per head.
The Americans who tried to fix Haiti up were no idiots. After all, FDR wrote the Haitian Constitution when he was Navy Secretary, and Woodrow Wilson was an impressive guy, kind of like Jimmy Carter with testicles. But it just didn't take. After the Marines left in 1934, the Army was about the only thing that was still running properly.
From 1934 to 1957, Haiti was even more messy than usual. It was "Coups R Us," with more name changes than the Golden State Warriors coaching staff. And about as much success, too.
A humble, smiling little black country doctor, Francois Duvalier, was the one man who figured out a way to bring the whole country under his control.
Problem #1 was the Army, because it could and did overthrow any President who got uppity. Problem #2 was bonding with the big "black" population who didn't know or care who was running the cities. Duvalier started by courting the black peasants. He talked a lot of "black and proud" stuff and got officially interested in Voodoo, which made the peasants feel like he was a homeboy and also scared the Hell out of them, since Duvalier let it be known that he was in touch with some very scary spirits.
Then he took on the Army. They'd put him in charge; now he wanted to make sure they could never take him out. He announced he was President-for-Life, but that didn't impress anybody. He was the eighth Haitian to claim that title. It meant about as much as a Don King title bout.