Haiti has been unstable politically and sercurity-wise. Leading up to World War I, the American government knew that Hispaniola was the key to stopping the Germans from setting up espionage and military in the Carribean. Both of these reasons led to the occupation: the Haitian government supported this occupation, in hopes of bringing stability and reforms to the nation. The occupation began on July 28, 1915, when 330 Marines landed at Port-au-Prince.
The Dominican occupation began on May 5, 1916, when Marines landed at the city of Santo Domingo. Reforms and improvements were brought to the country, although the people still resented the loss of their soveirgnity.
PoD (Less Harsh Laws)
The strict censorship laws and seeming no care for the wellbeing of the people of Dominican Republic (or as the Americans called it, Santo Domingo) in OTL are changed in this ATL. They granted the Santo Domingoans the freedoms of speech; the press; etc., and Americans worked to help improve the lives of peasants. Woodrow Wilson came to speak in Santiago in 1918, also helping to win over the people. All of this led to significantly less resistance than in OTL. While US influence was decreasing, and Juan Bautista Vicini Burgos became provisional president of the Dominican Republic, Warren G. Harding (who had developed a love for the Dominicans, unlike in OTL) made one last bid to keep Santo Domingo: annexation, where Burgos would become the first terriorial governor of the Commonwealth Santo Domingo. Burgos agreed to the annexation, seeing that his power would be secured but not reduced if Santo Domingo became a self-governing territory. Thanks to the less harsh laws and care for the wellbeing of the people, the populace of the Santo Domingo accepted the annexation. In hopes of a better future, the Haitian government agreed for Haiti to join the commonwealth. The occupations were over.