The Battle of San Jacinto (Spanish: Batalla de San Jacinto), fought on April 21, 1836, in present-day La Porte and Pasadena, Texas, was the final and decisive battle of the Texas Revolution. Led by General Samuel Houston, the Texan Army engaged and defeated General Antonio Lpez de Santa Anna's Mexican army in a fight that lasted just 18 minutes. A detailed, first-hand account of the battle was written by General Houston from the headquarters of the Texan Army in San Jacinto on April 25, 1836. Numerous secondary analyses and interpretations have followed.

General Santa Anna, the president of Mexico, and General Martn Perfecto de Cos both escaped during the battle. Santa Anna was captured the next day on April 22 and Cos on April 24. After being held for about three weeks as a prisoner of war, Santa Anna signed the peace treaty that dictated that the Mexican army leave the region, paving the way for the Republic of Texas to become an independent country. These treaties did not necessarily recognize Texas as a sovereign nation but stipulated that Santa Anna was to lobby for such recognition in Mexico City. Sam Houston became a national celebrity, and the Texans' rallying cries from events of the war, "Remember the Alamo" and "Remember Goliad" became etched into Texan history and legend.

The Texas Revolution (October 2, 1835 – April 21, 1836) was a rebellion of colonists from the United States and Tejanos (Hispanic Texans) in putting up armed resistance to the centralist government of Mexico. While the uprising was part of a larger one, the Mexican Federalist War, that included other provinces opposed to the regime of President Antonio López de Santa Anna, the Mexican government believed the United States had instigated the Texas insurrection with the goal of annexation. The Mexican Congress passed the Tornel Decree, declaring that any foreigners fighting against Mexican troops "will be deemed pirates and dealt with as such, being citizens of no nation presently at war with the Republic and fighting under no recognized flag". Only the province of Texas succeeded in breaking with Mexico, establishing the Republic of Texas, and eventually being annexed by the United States.

The revolution began in October 1835, after a decade of political and cultural clashes between the Mexican government and the increasingly large population of American settlers in Texas. The Mexican government had become increasingly centralized and the rights of its citizens had become increasingly curtailed, particularly regarding immigration from the United States. Mexico had officially abolished slavery in Texas in 1830, and the desire of Anglo Texans to maintain the institution of chattel slavery in Texas was also a major cause of secession. Colonists and Tejanos disagreed on whether the ultimate goal was independence or a return to the Mexican Constitution of 1824. While delegates at the Consultation (provisional government) debated the war's motives, Texians and a flood of volunteers from the United States defeated the small garrisons of Mexican soldiers by mid-December 1835. The Consultation declined to declare independence and installed an interim government, whose infighting led to political paralysis and a dearth of effective governance in Texas. An ill-conceived proposal to invade Matamoros siphoned much-needed volunteers and provisions from the fledgling Texian Army. In March 1836, a second political convention declared independence and appointed leadership for the new Republic of Texas.

Determined to avenge Mexico's honor, Santa Anna vowed to personally retake Texas. His Army of Operations entered Texas in mid-February 1836 and found the Texians completely unprepared. Mexican General José de Urrea led a contingent of troops on the Goliad Campaign up the Texas coast, defeating all Texian troops in his path and executing most of those who surrendered. Santa Anna led a larger force to San Antonio de Béxar (or Béxar), where his troops defeated the Texian garrison in the Battle of the Alamo, killing almost all of the defenders.

A newly created Texian army under the command of Sam Houston was constantly on the move, while terrified civilians fled with the army, in a melee known as the Runaway Scrape. On March 31, Houston paused his men at Groce's Landing on the Brazos River, and for the next two weeks, the Texians received rigorous military training. Becoming complacent and underestimating the strength of his foes, Santa Anna further subdivided his troops. On April 21, Houston's army staged a surprise assault on Santa Anna and his vanguard force at the Battle of San Jacinto. The Mexican troops were quickly routed, and vengeful Texians executed many who tried to surrender. Santa Anna was taken hostage; in exchange for his life, he ordered the Mexican army to retreat south of the Rio Grande. Mexico refused to recognize the Republic of Texas, and intermittent conflicts between the two countries continued into the 1840s. The annexation of Texas as the 28th state of the United States, in 1845, led directly to the Mexican–American War.