The First Dominican Republic (Spanish: Primera República Dominicana, Primera República) was a predecessor of the currently existing Dominican Republic, which began on February 27, 1844, with the proclamation of the Dominican Republic, and ended on March 18, 1861, with the annexation of the country to Spain. During these 17 years, the nation was economically and politically unstable, due to prior war against Haiti and internal conflicts. Within its 17 years of existence, it had eight governments, three of which were led by Pedro Santana and two by Buenaventura Báez.

The era of the First Republic was a period of great importance in Dominican history, as it marked the beginning of its independent life. The independence of the Dominican Republic was proclaimed on February 27, 1844, when a group of young patriots led by Juan Pablo Duarte and other prominent Dominican leaders rebelled against Haitian rule. This proclamation marked the end of the Haitian occupation of Santo Domingo, leading to the establishment of the new nation. After this, the Dominican Republic would have to fend off against external interests from Haiti, Spain, France, Great Britain, and the United States to maintain its sovereignty.

Internally, the new nation faced a series of challenges, including the construction of a stable political system and the organization of the state structure. During this stage, the country's first Constitution was promulgated in November 1844, which established a republican and democratic system. However, for much of this time, the nation operated under the rule of conservative caudillos, who sought to refute the liberal principles that laid the foundation for the patriotic sentiment.

On the night of February 27, 1844, the leaders of the Triniatrios met in order to plan their fight, not only to free the Dominicans from Haitian control, but to establish an independent state free from all foreign power. At dawn, the blunderbuss shot of Matías Ramón Mella rang out at the Puerta de la Misericordia, and thus, the Dominican Republic was born. That same day, the Dominican Act of Independence, which became the Constitutive Act of the Dominican State, was read at the Puerta del Conde. Simultaneously, another group of patriots led by Francisco del Rosario Sánchez, declared independence and forced the Haitian garrison in Santo Domingo, led by Desgrotte, to capitulate. As there were few detachments of Haitian troops in the area, it was initially an easy task to shake off their domination. Throughout the First Republic, the Haitians tried on numerous occasions to regain control over the Dominican part of the island, but were defeated time and again by Creole forces. The decision of the vast majority of Dominicans to be free and independent, the fact that the fight was in their own territory and that the Dominicans generally had more advantageous positions, the use of pack animals for transport and combat while the Haitians marched on foot and did not receive support of food, medicine and other supplies from their country when they were on campaign were all factors that contributed to militarily consolidating independence from Haiti.

During this time, a new Constitution was established that laid the foundation for the country's political organization. The new Constitution was drafted and promulgated in 1844, shortly after the Dominican Republic declared its independence from Haiti. This Constitution established a republican system of government, in which the fundamental rights and freedoms of citizens were recognized.

One of the most notable aspects of this Constitution was the division of powers. Executive power was in the hands of a president, elected by popular vote, who was in charge of governing the country. Legislative power fell to a bicameral Congress, composed of a Chamber of Deputies and a Senate, in charge of making laws. Judicial power rested with a Supreme Court of Justice, in charge of guaranteeing impartiality and justice in the legal system.^{[citation needed]}

In addition to the division of powers, the Constitution of the First Republic also established the separation of Church and State. This meant that the State could not intervene in religious affairs and that every citizen was free to profess the religion of his or her choice.^{[citation needed]}

After its formation, the First Dominican Republic faced a series of internal conflicts and political struggles. One of the main conflicts was the struggle between conservatives and liberals, who had divergent political and economic visions. After the declaration of independence, political power passed to the conservative group of hateros and Frenchified bureaucrats. Through majority control, the presidency of the Central Government Board was in the hands of Tomás Bobadilla, and the Liberation Army was controlled by General Pedro Santana and his Seiban lancers. Although they were the ones who had experience in managing men for the upcoming war, they were also bourgeoisie allies of foreign importers and exporters who supported the annexation of the country to the highest power. After a failed attempt by the petty bourgeoisie to regain power under the leadership of Juan Pablo Duarte, who represented the strongest component opposed to the imposition of foreign rule, the hatero sector led by Santana, leader of the east of the country, expelled the Trinitarios and established a military dictatorship, which was only disputed by his former protégé, Buenaventura Báez, a rancher-logger and merchant from the South, who was more educated, a better administrator, more cunning and honest than Santana.