The Battle of San Jacinto (21 April 1836) was the decisive engagement of the Texas Revolution in which General Sam Houston (1793 to 1863) defeated the Mexican Army under President and General Antonio López de Santa Anna (1794 to 1876) in 18 minutes. After Santa Anna was captured the next day, the Texian troops demanded his execution to avenge those who had fallen at the Battle of the Alamo and the Goliad Massacre. Houston was able to leverage this threat over the next few weeks to get Santa Anna to sign the Treaties of Velasco, withdrawing all Mexican troops from Texas and allowing for the birth of the Texas Republic.

The Texas Revolution began on 2 October 1835 with the Battle of Gonzales, and the Texian forces won every engagement for the rest of that year. Their luck changed when Mexican General José de Urrea (1797 to 1849) won a string of victories, defeating Texian forces at the Battle of San Patricio on 27 February 1836, at the Battle of Agua Dulce on 2 March, at the Battle of Refugio on 14 March, and the Battle of Coleto on 19 to 20 March.

Meanwhile, Santa Anna had besieged the Alamo at San Antonio de Béxar for 13 days (23 February to 6 March), finally ordering a pre-dawn assault on 6 March. All the defenders were killed in the battle or executed afterwards. Santa Anna demanded his officers adhere to the Tornel Decree of 30 December 1835, which defined all who took up arms against Mexico as "land pirates", fighting only for their own self-interest, who, therefore, should be shown no mercy. No prisoners would be taken by the Mexican army, according to his orders, and any rebel force that surrendered was to be executed.

After General Urrea defeated Colonel James W. Fannin (1804 to 1836) at the Battle of Coleto, Fannin surrendered on the understanding that, as prisoners of war, they would be disarmed and then allowed to return to the United States. Urrea had refused to follow Santa Anna's orders regarding prisoners at San Patricio, Agua Dulce, and – except for Captain Amon B. King and some of his men – at Refugio, choosing instead to send the Texians as prisoners to Matamoros. He left Colonel Nicolás de la Portilla in charge at Goliad, ordering him to continue this policy and treat the prisoners well.

Portilla, however, followed Santa Anna's directive, and, on 27 March 1836, 350 to 400 men of the garrison were marched out of the fort in three different directions and executed. The sick and wounded still inside Fort Defiance, including Colonel Fannin, were shot dead in the courtyard. This event became known as the Goliad Massacre.

While the siege of the Alamo was underway, and Urrea defeated the Texians at Agua Dulce, the provisional government of Texas, meeting at Washington-on-the-Brazos, declared Texas an independent republic. Houston had already been appointed commander of the regular army, but now his authority was enlarged to include any militia and the volunteers.

Houston left Washington-on-the-Brazos for Gonzales, arriving the afternoon of 11 March, where he planned to set up headquarters and wait for word from Colonel Fannin and his men. He had dismissed the reports of Lt. Colonel William Barret Travis (1809 to 1836), commander of the Alamo, that the fort was under siege and in need of reinforcement, considering them exaggerations. Houston did not believe Santa Anna's army had even entered Texas yet.

That evening, two Tejanos from San Antonio de Béxar – Andres Barcena and Anselmo Vergara – arrived at Gonzales with the news that the Alamo had fallen and there were no survivors. The news plunged the Gonzales community – who had many men at the Alamo – into grief. Houston rejected the report, however, and had the two men arrested as spies.

Two days later, however, Susanna Dickinson, wife of the artillery commander at the Alamo, Almaron Dickinson, along with her daughter Angelina and Travis' slave, Joe, reached Gonzales with the same report. Houston could not dismiss Dickinson's account. Scholar J. R. Edmondson writes:

Houston realized that, if a slow-moving party of survivors could reach Gonzales from Béxar, so could the Mexican army. And he did not have enough men to fight.

(393)

He ordered Gonzales evacuated and the town burned. This began the event known as the Runaway Scrape, in which Texians – not just at Gonzales but everywhere – fled east to escape the Mexican army. They took what could be carried, burned the rest, and left their homes on the night of 13 March. Houston gathered his troops – mainly the 400 men who had been waiting at Gonzales for Fannin to arrive and lead them to reinforce the Alamo – and led his men in retreat toward the Colorado River, sending word to Fannin to meet him there. Juan Seguin and his Tejano cavalry served as the rear guard on the retreat.

Mexican General Ramírez y Sesma, under Santa Anna's command at San Antonio de Béxar, arrived at Gonzales with his cavalry on 14 March and found only smoking ruins. He was informed of Houston's flight toward the Colorado River and set out instantly in pursuit. Houston, meanwhile, was moving slowly, traveling not only with his army but also with civilians from Gonzales and elsewhere. Juan Seguin, commanding the rear guard, delayed Sesma. Edmondson writes:

The bitter cold winter had transformed into a wet spring…The army trudged through quagmires that once had been roads. They reached the flooded Colorado River on March 17. The army helped the civilians cross first. Houston's men finally forded the river on March 20. Just in time. General Sesma, with eight hundred troops and two cannons, arrived on the west bank the next day.

(394)

As Houston had been marching, news of the fall of the Alamo had spread, and more volunteers joined his ranks. By the time he crossed the Colorado River, he had around 1,400 under his command. He expected to be reinforced by Fannin and his garrison of 400, but, on 20 March, received the news of Fannin's surrender at the Battle of Coleto and understood that his army was now the only hope of winning the Texas Revolution.

His men, wanting to avenge those who fell at the Alamo, demanded they be allowed to engage Sesma as Seguin and his cavalry had, but Houston held them back. He had no artillery, most of his men were untrained, and Sesma would have been able to easily cut the Texians down with cannon fire as they crossed back across the river. Houston's men obeyed his orders, but unwillingly, and afterwards many would desert, believing Houston was a coward, interested only in retreat.

After the fall of the Alamo, Santa Anna remained at Béxar, directing the war from a commandeered home. He sent Sesma toward Gonzales with orders to proceed from there to San Felipe and Washington-on-the-Brazos. He then sent General Gaona toward Nacogdoches to disperse any rebels there, and Colonel Juan Morales was ordered to reinforce General Urrea's Goliad campaign.

Santa Anna was bored with Texas and the war, and was thinking of returning to Mexico City, but feared that Urrea – who had won four victories to Santa Anna's one – would capitalize on this and unseat him as president. Scholar Stephen L. Hardin comments:

Near the end of March, Santa Anna and his staff departed Béxar, the town for which his army had paid so dearly. He reached the combined forces of Tolsa and Ramírez y Sesma on April 4. By then the floodwaters had subsided and the Mexicans spent the next day fording the Colorado…Once across the river, he advanced that same day to the banks of San Bernardo Creek, some thirteen miles to the north.

(185 to 186)

Arriving in San Felipe with Tolsa and Sesma, Santa Anna found the town in ashes. Learning that the provisional government was at Harrisburg, he hurried there only to learn that President David G. Burnet and the others had just left for New Washington. He ordered Colonel Juan Almonte to take 50 cavalry and capture them. Almonte arrived just as Burnet and the others were leaving by boat, and could have easily shot them all from the shore, but Almonte saw Mrs. Burnet in the boat and refused to fire on a woman, so the provisional government escaped. Almonte then rejoined Santa Anna at Harrisburg.

Houston's army, meanwhile, continued in retreat and reached Groce's Landing on 31 March. Scholar James Donovan writes:

They made camp in the Brazos bottomlands at Groce's plantation on March 31, just in time to hear the shocking fate of Fannin's men, massacred four days earlier. The news only heightened the panic, and hundreds of Houston's volunteers took furloughs or deserted to assist their families in their flight east . The army shrank to eight hundred stalwarts. Houston spent the next two weeks training his rabble and instilling discipline. While his men talked of mutiny, and of replacing him with someone more aggressive, he spent his nights pondering strategy, usually alone.

(322 to 323)

On 7 April, Thomas J. Rusk (1803 to 1857), Interim Secretary of War, arrived in Houston's camp with a message from President Burnet for Houston, which read:

The enemy are laughing you to scorn. You must fight them. You must retreat no further. The country expects you to fight. The salvation of the country depends on your doing so.

(Edmondson, 396)

Rusk delivered the message and informed Houston that he had orders to replace him as general if he would not make a stand and fight. Houston explained his strategy to Rusk, who accepted his arguments, and Houston kept his command.

Houston broke camp and crossed the Brazos River. On 12 April, two cannons arrived from Cincinnati, Ohio, and were named the Twin Sisters. Colonel James C. Neill (circa 1788 to 1849), who had turned over command of the Alamo to Travis in early February, was commissioned as an artillery officer.

Houston's army marched eastward. On 16 April, they approached a crossroads and, in the center, stood a large oak (later known as the Which Way Tree). The road to the right led to Harrisburg and Santa Anna; the road to the left led toward Nacogdoches, safety, and further retreat. As the troops reached the tree, they spontaneously took the road to Harrisburg.

They arrived on 18 April to find the town burned and Santa Anna gone. Houston's scout, Erastus "Deaf" Smith (1787 to 1837), captured a Mexican courier there carrying documents on Mexican troop movements in a saddlebag with "W. B. Travis" marked on it. Houston, seeing where Santa Anna was heading, rallied his men with a speech including the famous lines, "Remember the Alamo! Remember Goliad!" and then quick-marched the men toward Lynch's Ferry near the San Jacinto River.

20 April

Houston arrived at Lynch's Ferry first. Edmondson writes:

On April 20, with the San Jacinto River to his left, and Buffalo Bayou behind him, Houston established his camp amid moss-draped trees. Ahead of him, to the southeast, extended a mile-wide prairie of tall, waving grass. (398)

Santa Anna arrived later and was pleased to see that Houston had seemed to have trapped himself in a position where he would have to fight to the death or retreat into the waters of the bayou. However, as Edmondson notes:

Santa Anna's location was hardly better than Houston's. He was backed up against boggy lagoons that could impede his own retreat. (399)

Santa Anna's senior staff, in fact, objected to the location. Hardin notes:

Colonel Pedro Delgado was amazed that the general would select such a vulnerable campsite. It was "in all respects against military rules. Any youngster would have done better," he observed. (202)

Houston's position was actually much stronger. His men knew the terrain better, and his army was sheltered by the trees. Although Santa Anna seemed to believe the Texians could not retreat through the waters of the bayou, these men had already endured far worse on their march from Gonzales. A small rise across the field between the two camps – approximately 500 yards (460 m) apart – concealed them from each other, and Santa Anna decided to test the strength of Houston's army by firing his 12-pound Golden Standard cannon at them.

Colonel Neill responded with the Twin Sisters and an artillery duel ensued. Neill was wounded in the hip and taken to a nearby home. The Twin Sisters performed better than the Golden Standard, and, fearing he might lose the only cannon the Mexicans had, Colonel Delgado ceased fire and withdrew.

Houston's men then wanted to charge. Sidney Sherman was especially anxious to avenge the Alamo and Goliad. Houston refused – but told him he could go out and reconnoiter but should not engage. Sherman ignored these orders and led a charge on the Mexican position, which was repulsed, and Thomas Rusk, riding with Sherman, was nearly captured before he was rescued by Mirabeau B. Lamar. Houston was furious and refused any further discussion of engagement. He ordered the men to sleep in preparation for battle.

Meanwhile, Santa Anna ordered his men to prepare defenses. He believed Houston would attack before dawn, just as Santa Anna had himself at the Alamo. All through the night, the Mexican army made breastworks out of anything at hand, dug trenches, and stood guard. Consequently, none of them would have had much sleep the next day.

21 April

At around 9:00 a.m. on the 21st, General Cos arrived with reinforcements, bringing Santa Anna's army up to 1200 to 1300 against Houston's force of around 900. Cos' men had marched through the night, and those already encamped had been hard at work. As no attack came at dawn, and there was no sign of movement from the Texian side, Santa Anna ordered the men to rest and eat.

Across the field, Houston sent "Deaf" Smith to destroy Vince's Bridge, approximately 8 miles (13 km) away, the only means of entrance or exit from the battlefield. This would prevent further reinforcements for Santa Anna as well as any attempt on his part to retreat.

As the day wore on, and there was no sign of an impending attack, Santa Anna and his men relaxed further. Meanwhile, Houston organized his men with two lines of infantry, the Twin Sisters in the center, and cavalry on the right flank. Around 3:30 p.m., the Texian army began a slow advance through the tall grass, halting only 200 yards (182 m) from the Mexican breastworks. At 4:30 p.m., Houston sounded the charge, the Twin Sisters fired, and the Texians sprang from the grass and overran the Mexican defenses, yelling, "Remember the Alamo! Remember Goliad!"

The battle was over in 18 minutes. The Mexican army had been taken completely by surprise – many of them deeply asleep – and the battle quickly turned into a massacre. Edmondson writes:

The subsequent slaughter would endure more than an hour. The enraged Texians had learned from Santa Anna the meaning of "no quarter." As they pursued the fleeing soldiers through the tents, the Texians shot and clubbed and slashed every Mexican they overtook. The soldiers who dropped to their knees, pleading, were more easily dispatched.

Houston, Rusk, and some of the other officers galloped through their midst, trying to restore order and end the massacre. "Gentlemen!" Houston bellowed with obvious irony, "I applaud your bravery. But damn your manners!"

In their flight, a large number of Mexicans splashed into the lagoons behind their camp, only to become bogged down in thigh-deep mud. They made easy targets for the Texians standing on the bank…the bloodlust finally faded with the sunlight and the Texians began collecting prisoners.

(402)

Santa Anna, however, was not among the dead or captured. He had fled toward Vince's Bridge during the battle and, finding it destroyed, hid in the marshes overnight. Mexican army casualties numbered over 600, while the Texians would lose 11 killed in battle or dying later from their wounds.

22 April

Houston had had two horses shot out from under him, and one shot had shattered his ankle. He was resting beneath a tree the next day when Santa Anna was found in the marsh, dressed in the uniform of a foot soldier. His identity was revealed by other captives who called out to him as their leader, and he was quickly brought to Houston.

The Texians wanted Santa Anna executed immediately, but Houston recognized the general was worth far more alive. Santa Anna's army was only one of many in Texas at that moment, and Houston did not believe he could beat Urrea or Morales as easily as he had Santa Anna. Urrea, from the moment he crossed into Texas, had not lost a single engagement. Houston, therefore, had Santa Anna send out a general order to his officers, telling them of his defeat, and that they must immediately retreat to Béxar to await further instruction.

Over the next few weeks, Santa Anna negotiated with Houston and Burnet, finally signing the Treaties of Velasco that mandated the removal of all Mexican troops from Texas, ending Mexican military control of the region. He also promised to convince the Mexican Congress to recognize the new Texas Republic.

While he had been away, however, Santa Anna had been deposed, and the Mexican government was not about to honor any documents signed or promises made by a prisoner of war with no political power. They refused to recognize Texas' independence and, in fact, commissioned Urrea to return and retake the region. He was only prevented from this by more pressing rebellions throughout Mexico.

The Battle of San Jacinto won Texas its independence, establishing the Texas Republic, which would last for ten years before it was annexed by the United States. Annexation set off the Mexican-American War (1846 to 1848), won by the US, and resulting in the Mexican Cession of lands including modern-day California and New Mexico, expanding the territory of the United States to the West Coast.