Texas, Republic of, was an independent country in what is now the eastern part of the state of Texas. The republic formed in 1836, during a revolt by American colonists against Mexican rule. It existed until 1845. That year, Texas became the 28th state of the United States. Disputes over Texas’s boundaries led to hostilities between Mexico and the United States.
Background.
Starting in the late 1600’s, Spanish priests established Roman Catholic missions in what is now eastern Texas. In 1718, the Spanish founded San Antonio and built a fort and mission there. The city later became the seat of Spanish government in Texas. The mission became known as the Alamo. In 1821, Mexico gained its independence from Spain. Texas became part of Mexico. 
Moses Austin was a Missouri mine owner. In 1821, he gained permission from Spanish officials in Mexico to start a colony of Americans in Texas. His son, Stephen F. Austin, organized the colony. Other American organizers also established colonies in the area. By the mid-1830’s, about 30,000 Americans lived in Texas.
Around 1830, Mexican officials attempted to halt American immigration to Texas. Relations between the American colonists and the Mexican government grew steadily worse. In 1834, Antonio López de Santa Anna, a Mexican general and politician, overthrew Mexico’s government. The following year, the American colonists in Texas revolted against Mexican rule. Many of the Mexican colonists in Texas also supported the revolt.
Revolution.
In November 1835, Texas leaders organized a temporary government. The following month, Texas troops took control of San Antonio. A large Mexican army led by Santa Anna then marched on the city. Santa Anna’s forces attacked the Alamo on Feb. 23, 1836. The building’s defenders included the American frontiersmen Jim Bowie and Davy Crockett. Santa Anna’s forces killed all the defenders, and the Alamo fell on March 6.
On March 2, Texas leaders issued a declaration of independence from Mexico. They chose David G. Burnet as Texas’s temporary president. They named Sam Houston commander of the army.
Later in March, Santa Anna ordered more than 300 Texas prisoners shot to death at Goliad, Texas. “Remember the Alamo” and “Remember Goliad” became rallying cries for Texas independence. On April 21, Sam Houston’s army, despite being outnumbered, defeated Santa Anna’s forces at the Battle of San Jacinto. The victory ensured Texas independence.
Republic and statehood.
In September 1836, voters approved Texas’s constitution and elected government leaders. Texas’s first Congress, which consisted of a Senate and House of Representatives, met in early October. Later that month, Sam Houston took office as the first president. During the years of the Republic of Texas, Texas’s population increased rapidly. The cities of Houston, Austin, and Washington-on-the-Brazos served as early Texas capitals. Austin became Texas’s permanent capital in 1845.
Texans had voted to join the United States in 1836. However, the Northern States blocked Texas’s annexation, largely because Texas allowed slavery. In 1844, the U.S. Senate defeated a treaty to annex Texas to the United States. Texas finally joined the Union on Dec. 29, 1845. It became the 28th state by a joint resolution of both houses of Congress.
After Texas joined the Union, Mexico ended diplomatic relations with the United States. In 1846, President James K. Polk sent U.S. troops to the Rio Grande, into territory claimed by both Texas and Mexico. The move led to the Mexican War (1846-1848). Mexico surrendered in 1848. In the Treaty of Guadalupe Hidalgo, Mexico gave up all claims to Texas and other southwestern lands.
