“Remember the Alamo!”

“Remember the Alamo!” was the war cry at the battle of San Jacinto on April 21, 1836, about a month after the fall of the Alamo. The Texas forces, led by commander-in-chief Sam Houston, won a quick victory in a mere twenty minutes over Santa Anna’s Mexican forces.
 
The battle cry “Remember the Alamo!” comes from the troops in that San Jacinto battle led by Colonel Sidney Sherman. Sam Houston’s April 25th letter—widely reprinted in newspapers (below)—is our best evidence of the battle cry.
   
   
American Heritage Dictionary of American Quotations
edited by Margaret Miner and Hugh Rawson
New York: Penguin Reference
1997
Pg. 27:
Remember the Alamo!
—SIDNEY SHERMAN, battle cry, April 31, 1836.
[The saying is traditionally attributed to Col. Sherman, whose troops advanced at San Jacinto chanting this battle cry. One month earlier, Gen. Santa Anna, the president of Mexico, had conquered the Alamo, leaving no survivors. In the battle of San Jacinto, Texans led by Commander in Chief Sam Houston, captured Santa Anna. In the Treaty of Velasco, which Santa Anna was forced to sign, Mexico recognized the independence of Texas.]
 
Wikipedia
The Battle of the Alamo was a 19th-century battle between the Republic of Mexico and the rebel Texan forces, including Tejanos, during the latter’s fight for independence - the Texas Revolution. It took place at the Alamo mission in San Antonio, Texas (then known as “San Antonio de Béxar”) in February and March of 1836. The 13-day siege ended on March 6 with the capture of the mission and the death of nearly all the Texan defenders, except for a few slaves, women and children. Despite the loss, the 13-day holdout stalled Mexican forces’ progress and allowed Sam Houston to gather troops and supplies for his later successful battle at San Jacinto.. The Texan defenders went on to win the war.
 
Wikipedia
The Battle of San Jacinto, fought on April 21, 1836, was the decisive battle of the Texas Revolution. Led by General Sam Houston, the Texas Army engaged and defeated General Antonio López de Santa Anna’s Mexican forces. Hundreds of Mexican soldiers were killed or captured, while there were relatively few Texan casualties.
(...)
On April 21, at 4:30 p.m. after the burning of Vince’s Bridge the Texan attack began. Marching to “Will you come to the bower I have shaded for you”, Sam Houston’s army is one of the few that ever marched to a love song. The Texan army moved quickly and silently across the high-grass plain, then when they were only a few dozen yards away, charged Santa Anna’s camp shouting “Remember the Alamo” and “Remember Goliad”, only stopping a few yards from the Mexicans to open fire. Confusion ensued. Santa Anna’s army were professional soldiers, but were trained to fight in ranks, exchanging volleys with their opponents; also ill-prepared and unarmed, at the time of the attack. Thousands of miles away, without their leader Santa Anna (he wasn’t even present), the demoralized and confused Mexicans retreated. Many Mexican soldiers ran into the marshes along the river. Some of the Mexican army rallied and attempted to push the Texans back, but their training left them ill-equipped to fight well-armed American frontiermen in hand-to-hand combat. During the battle, Houston was wounded in the left ankle and Santa Anna escaped. In 20 minutes, the Texan army had won, killing over 600 Mexican soldiers and taking 730 prisoners.
 
9 June 1836, Macon (GA) Weekly Telegraph, pg. 2:
From the New Orleans Bulletin May 25.
HEAD QUARTERS OF THE ARMY, SAN JACINTO, April 25th, 1836.
To His Excellency D. G. Burnvile, President of the Republic of Texas
 
SIR—I regret extremely that my situation since the battle of the 21st has been such as to prevent my rendering you my offered report of the same previous to this time.
 
I have the honor to inform you, that on the evening on the 18th inst., after a forced march of fifty five miles, which was effected in two days and a half; the army arrived opposite Harrisburg; a courier of the enemy was taken, from whom I learned that Gen. Santa Ana, with one division of his choice troops had marched in the direction of Lynch’s ferry on the San Jacinto, burning Harrisburg as he passed down.
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Col. Sherman with his regiment having commenced the action upon our left wing, the whole line at the centre and on the right, advancing in double quick time, rung the war cry “Remember the Alamo.” Receiving the enemy’s fire, and advancing within point black shot before a piece was discharged from our lines. Our line advanced without a halt, until they were in possession of the woodland and the enemy’s breastwork.
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I have the honor to be,
With high consideration,
Your obedient servant,
SAML. HOUSTON
Commander-in-Chief.