The Alamo (Spanish: álamo; referring to the genus Populus, i.e cottonwood or poplar trees) is a former Spanish mission located in downtown San Antonio, Texas, and was an abandoned ruin when it was used as a fortification in 1836 by colonists against the harsh rule of dictator Antonio Lopez de Santa Anna; the resulting siege and massacre of the 189 men within led to Santa Anna's defeat at San Jacinto a short time later and the creation of the independent Republic of Texas.
Misión San Antonio de Valero was one of five missions constructed in the region that was later to become San Antonio de Bexar; the Valero mission's foundation was laid in 1724, and served the area for some seventy years. About 1793 the missions and the land they were on were divided and given over to the control of the Indian inhabitants, who continued to be productive farmers in the small San Antonio community while the mission buildings lay abandoned.
The Valero mission was inhabited again in the early-1800's, this time by a contingent of cavalry soldiers from the Coahuila town of Alamo de Parras, who gave the old ruins its present name from the familiar cottonwood trees which had grown about the site. The commander of the unit would build and establish the first hospital in Texas in what is called the Long Barrack, a structure built in front of and to the north of the main church building. The West Wall and South Barrack structures would be built prior to 1830, as the Alamo site grew into a fortification which served the military units of Spain and Mexico.
In the early 1820’s Americans began arriving in Tejas – the territory of Mexico north of the Rio Grande river – for the purpose of colonization. Sparsely-populated and un-productive at the time, the colonists soon turned the territory into Mexico’s most prosperous, with the additional benefit of strengthening Mexico’s claim to the area. Under the auspices of the constitution of 1824, the Texians (as the colonists called themselves) had the promise of having the territory admitted to Mexico as a state. Up until 1830 there was mutual respect between the central government and the colonists under Stephen F. Austin, who had made yearly trips to Mexico City as an act of fealty and to update the government on their progress. The relationship soured somewhat beginning in 1830, when Mexico's president Anastasio Bustamante became increasingly hostile towards the colonists, enacting higher taxes and duties, restricting shipping on the coast, and cancelling land contracts. In 1832 Butamante was overthrown in a coup led by Santa Anna, and for a short period the colonists enjoyed a respite, which ended when Austin again made a trip to Mexico City and was promptly thrown into jail for daring to petition the government to admit Texas as a state under the 1824 constitution; he would remain there for eighteen months, and be released in the summer of 1835.
During his absence unrest continued to grow within the Tejas areas settled by the colonists, directed against the increasingly harsh rule of Santa Anna, now recognized as a dictatorship as he consolidated his power following the coup. Several settlements were occupied by Mexican regulars; the town of Bexar (San Antonio) was taken by General Marín Perfecto de Cós in the fall of 1835; and Lt. Francisco Castaneda with one hundred men was sent to the town of Gonzales to remove a cannon given to the settlers as a protection against Indian attacks. Not all went as planned: Castenada not only met stiff resistance from the settlers, but had to do so while looking at a white flag with the derisive words "Come and take it" printed on it. 
In December 1835, a force of Texians, Tejanos, and other volunteers under Ben Milam took Bexar after five days of fighting and compelled the surrender of Cós. The Alamo, strengthened considerably, was then occupied as a fortress.
Battle of the Alamo
Colonel James Clinton Neill was placed in command of the Alamo, and he immediately set to improving the defenses; however, both himself and his superior, General Sam Houston, knew that it was only a matter of time before Centralist troops arrived in force. On January 17, 1836 Houston informed provisional governor Henry Smith that an abandonment of the Alamo was necessary. "I have ordered the fortifications in the town of Bexar to be demolished," he wrote, "and, if you should think well of it, I will remove all the cannon and other munitions of war to Gonzales and Copano, blow up the Alamo and abandon the place, as it will be impossible to keep up the Station with volunteers, the sooner I can be authorized the better it will be for the country." Regular soldiers stationed within Bexar were few - about thirty men - and there were a slightly larger number of volunteers. Smith decided against abandoning the Alamo.
On the same day Houston wrote his message another group of volunteers arrived under the command of Colonel James Bowie, a proven fighter whose favorite weapon was a massive knife which bears his name. Neill soon convinced Bowie to stay, convincing him that the Alamo was the only defensive fortification along the camino real between Santa Anna's forces and the Anlgo settlements to the north. Bowie's letter to Smith describing the nature of the defences and his resolve to never surrender the fort may have played a role in turning down Houston's request; nevertheless the governor managed to send additional troops and provisions.
On February 3, a unit of cavalry arrived in Bexar under orders from Smith and reported to Neill; its commander was Lt. Colonel William B. Travis, who was made second-in-command; he would himself be in command - albeit temporarily - when Neill left on an emergency furlough on February 14. Despite being sent to Bexar against his wishes, Travis was soon committed to the Alamo, calling it "the key to Texas". During this time other volunteers trickled in, some from Goliad, others from Gonzales, and one large group from Tennessee under a one-time United States Congressman and frontiersman who was a legend in his own lifetime, Davy Crockett. The number of fighting men swelled to 189.
Santa Anna was not expected to cross the Rio Grande until the middle of March, yet he arrived in the area on February 23 with more than 2,000 men. A courier was sent to the Alamo to demand the surrender of the garrison; the reply came from a cannon lit by Travis. Knowing that their only hope at withstanding a siege came from reinforcements, Travis penned a letter: 
- Commandancy of the Alamo
- Bexar, Fby. 24th, 1836
- To the People of Texas & all Americans in the world
- Fellow Citizens & Compatriots
- I am besieged by a thousand or more of the Mexicans under Santa Anna. I have sustained a continual bombardment & cannonade for 24 hours & have not lost a man. The enemy has demanded a surrender at discretion, otherwise the garrison are to be put to the sword if the fort is taken. I have answered the demand with a cannon shot, and our flag still waves proudly from the walls. I shall never surrender nor retreat.
- Then, I call on you in the name of Liberty, of patriotism, & of everything dear to the American character, to come to our aid with all dispatch. The enemy is receiving reinforcements daily & will no doubt increase to three or four thousand in four or five days. If this call is neglected, I am determined to sustain myself as long as possible & die like a soldier who never forgets what is due to his own honor & that of his country.
- Victory or Death
- William Barret Travis
- Lt. Col. Comdt.
- P. S. The Lord is on our side. When the enemy appeared in sight we had not three bushels of corn. We have since found in deserted houses 80 or 90 bushels & got into the walls 20 or 30 head of Beeves.
Assault of March 6
On March 5 Santa Anna declared to his officers that a general assault on the Alamo would take place the following morning, despite objections that a surrender was possible due to no relief coming and the fort crumbling. At 5 AM around 1,800 troops massed forward, to be met with canister shot from the Texian artillery. Reforming, they went forward again, this time breaching the defensive perimeter on all sides; Travis died on the north bastion. Vicious hand-to-hand fighting occurred as the Texians fell back to the Long Barracks. In the South Barracks Bowie - out of the battle since the first day of the siege with pneumonia - was bayoneted in his cot. The remaining defenders fell some 90 minutes after the assault began.
Only fourteen people survived the siege and final assault.
- Susanna Dickinson, wife of Capt. Almeron Dickinson;
- Angelina Dickinson, their 15-month old daughter;
- Joe, Travis' slave;
- Gertrudis Navarro;
- Juana Navarro Alsbury;
- Alijo Perez;
- Ana Esparza, (wife of Gregorio Esparza), and their four children:
- Maria de Jesus Castro;
- Trinidad Saucedo;
- Petra Gonzales;
- Brigido Guerrero, a deserter from the Mexican Army who talked his way out of being killed by claiming to be a POW.
It was claimed - with some credibility - that there were seven Texians who surrendered, among them Crockett. Lt. Col. José Enrique de la Peña, an officer under Santa Anna during the battle, wrote a personal journal describing the battle, Crockett's surrender, and execution:
"Some seven men survived the general carnage and, under the protection of General Castrillón, they were brought before Santa Anna. Among them was one of great stature, well proportioned, with regular features, in whose face there was the imprint of adversity, but in whom one also noticed a degree of resignation and nobility that did him honor. He was the naturalist David Crockett, well known in North America for his unusual adventures, who had undertaken to explore the country and who, finding himself in Béjar at the very moment of surprise, had taken refuge in the Alamo, fearing that his status as a foreigner might not be respected. Santa Anna answered Castrillón's intervention in Crockett's behalf with a gesture of indignation and, addressing himself to the sappers, the troops closest to him, ordered his execution. The commanders and officers were outraged at this action and did not support the order, hoping that once the fury of the moment had blown over these men would be spared; but several officers who were around the president and who, perhaps, had not been present during the danger, became noteworthy by an infamous deed, surpassing the solders in cruelty. They thrust themselves forward, in order to flatter their commander, and with swords in hand, fell upon these unfortunate, defenseless men just as a tiger leaps upon his prey. Though tortured before they were killed, these unfortunates died without complaining and without humiliating themselves before their torturers." 
The Mexican forces lost more than 1,500 men. The massacre at the Alamo was memorialized in the cry, "Remember the Alamo!" and helped to galvanize resistance to Santa Anna, who would go on to Goliad and stage another massacre of the defenders there. On April 21, 1836, the Mexican leader was caught napping at San Jacinto near present-day Houston and soundly defeated, ensuring Texas independence.
On January 13, 1841, the Republic of Texas passed an act restoring the Alamo and its grounds to the Catholic Church, but by then the Alamo was in ruins and no attempts were made at restorations. At various times during the next forty years the grounds were used as a military storehouse, despite the conflicting claims of ownership between the church, San Antonio, and the United States Government, which claimed the site after the annexation of Texas in 1848. In 1876, title to the property was passed back to the church.
In 1883 Texas purchased the property outright, and gave custody of it to San Antonio. Business concerns already owned part of the Alamo grounds until 1905, when the state legislature passed a resolution ordering the governor to purchase those grounds, and along with the chapel structure they were delivered into the custody of the Daughters of the Republic of Texas.