In early October of 1937, between 15,000 and 35,000 Haitians were massacred by order of Dominican dictator Rafael Trujillo. Some Haitians had become "foreign" when the border between the two countries was established in 1929, while others had crossed into the Dominican Republic a decade earlier to work on the sugar plantations. With the low commodity prices of the depression, they had become unwelcome guests -- and the unlucky objects of a century and a half of antihaitianismo.
According to Michele Wucker's book Why the Cocks Fight: Dominicans, Haitians and the Struggle for Hispaniola (New York: Hill & Wang, 1999. Copyright Michele Wucker, used by permission):
Trujillo's men searched the houses and estates of the region one by one, rounding up Haitians and initiating deportation proceedings against them; once the paperwork was done, the Dominican government had `proof' that the Haitians had been sent back to Haiti. The Haitians then were transported like cattle to isolated killing grounds. The soldiers slaughtered them at night, then carried the corpses to the Atlantic Ocean, at the customs port in Montecristi, and threw the bodies to the sharks. For days, the waves carried uneaten body parts until they washed up on the beaches.
Often, the soldiers did not even bother with the charade of covering up their crimes. Entire families were mutilated in their homes. For Haitians away from their homes, in the streets or in the fields, the soldiers applied a simple test. Since Haitians are considerably darker than most Dominicans, soldiers would accost a man or woman with dark skin. Holding up sprigs of parsley, Trujillo's men queried their prospective victims: `Como se llama ésto?' `What is this thing called?' The terrified victim's fate lay in his pronunciation of the answer. For Haitians, whose Kreyol language uses wide, a flat `R', it is difficult to pronounce the trilled `R' in the Spanish word for parsley, `perejil.' If the word came out as the Haitian `pe'sil,' or a bastardized Spanish `pewehí' the victim was condemned to die.
A fuller account, kindly provided by the author in the form of excerpts from the chapter in her book dealing with the massacre, is available here.
The massacre forms the background of Edwidge Danticat's novel The Farming of Bones.