The Siege of Fort Texas in 1846

May 3, 1846–May 9, 1846

The Siege of Fort Texas was fought between the United States of America and Mexico from May 3 to May 9, 1846, during the Mexican-American War. Mexican forces were unable to capture the fort and were forced to withdraw after losing battles at Palo Alto and Resaca de la Palma. The American victory at Fort Texas helped secure American control of the Rio Grande River.

James K Polk, 11th President, Portrait

President James K. Polk. Image Source: National Portrait Gallery.

Siege of Fort Texas Summary

The Siege of Fort Texas followed the Thornton Affair in the early days of the Mexican-American War. It took place at Fort Texas on the north bank of the Rio Grande across from Matamoros, Mexico. The fort was built by Brigadier General Zachary Taylor’s Army of Occupation in territory that was claimed by both Mexico and the United States. In May 1846, Mexican General Mariano Arista laid siege to the fort, firing around 3,000 rounds during the week-long bombardment. However, the fort’s defenders held strong, and Taylor’s men lifted the siege, defeating Arista’s forces at Palo Alto and Resaca de la Palma. The fort was renamed Fort Brown in honor of Major Jacob Brown, who was killed during the siege.

Siege of Fort Texas Facts

  • Date Started: The Siege of Fort Texas started on May 3, 1846.
  • Date Ended: It ended on May 9, 1846.
  • Location: The Siege of Fort Texas took place near present-day Brownsville, Texas.
  • Campaign: The battle was part of the Texas Campaign of the Mexican-American War.
  • Who Won: The United States won the Siege of Fort Texas.
  • Interesting Fact: Following the siege, Fort Texas was renamed Fort Brown, in honor of its fallen commander, Major Jacob Brown.
Siege of Fort Brown, Map, 1846
This map shows the location of forces around Matamoros, including Fort Texas. Image Source: A Complete History of the Mexican War, 1849,

Siege of Fort Texas History and Overview

During the Texas Revolution (1836–1836), Mexico believed the United States encouraged the uprising for the purpose of annexing Texas. After the Republic of Texas was established, Mexico threatened to declare war on the United States if it annexed Texas. As a result, the United States did not make any attempt to annex Texas until 1844. Texas was formally admitted to the Union on December 29, 1845, as the 28th state.

The Nueces Strip — Disputed Territory Between Mexico and the United States

Not only did the United States gain Texas, but it also inherited the ongoing border dispute between Texas and Mexico. Following the Battle of San Jacinto (1836), which ended the Texas Revolution, General Antonio López de Santa Anna agreed to the Treaties of Velasco. The treaties identified the Rio Grande River as the southern border of Texas. 

However, the Mexican Government never approved the treaties or recognized the independent Republic of Texas. As a result, Mexico insisted the southern border of Texas was the Nueces River, not the Rio Grande River. The disputed territory between the Nueces and the Rio Grande was known as the “Nueces Strip.”

When the United States annexed Texas in 1845, American officials hoped it would give them an opportunity to discuss the border with Mexico. However, it did not happen as Mexico cut off diplomatic ties with the United States.

The United States Army of Observation Moves into Texas

After Mexico cut off diplomatic relations with the United States, President James K. Polk ordered General Zachary Taylor to take command of an “Army of Observation.” Polk ordered Taylor to take the 3,500 men and march into Texas up to the Nueces River, on the border of the Nueces Strip. Taylor marched into Texas and established a camp at Corpus Christi, where the Nueces River flows into the Gulf of Mexico. From there, Taylor drilled and trained his men for seven months.

It is widely believed that Polk, a staunch believer in the idea of America’s Manifest Destiny, was looking to provoke Mexico into war with the United States. The purpose was to claim California, New Mexico, and the Nueces Strip. On March 8, 1846, ordered Taylor to cross the Nueces, into the Nueces Strip, down to the Rio Grande — which Texans and Polk claimed was the true southern border of Texas. 

Taylor and his men built Fort Texas near present-day Brownsville, Texas, on the north side of the Rio Grande. It was directly across from the town of Matamoros, Mexico. In response, Mexican General Mariano Arista demanded that Taylor withdraw from his camp and move back north of the Nueces River. However, Taylor refused the request and Arista marched his army toward Fort Texas.

Taylor and his men built Fort Texas near present-day Brownsville, Texas, on the north side of the Rio Grande. It was directly across from the town of Matamoros, Mexico. In response, Mexican General Mariano Arista demanded that Taylor withdraw from his camp and move back north of the Nueces River. However, Taylor refused the request and Arista marched his army toward Fort Texas.

General Zachary Taylor, Mexican American War
General Zachary Taylor. Image Source: Library of Congress.

Construction of Fort Texas

Fort Texas, later renamed Fort Brown, was built by Brigadier General Zachary Taylor’s Army of Occupation in the early spring of 1846. The fort was located on the north bank of the Rio Grande, opposite the Mexican village of Matamoros, near modern-day Brownsville, Texas. 

In February 1846, Taylor received orders from President James K. Polk to establish a supply base at Point Isabel. Taylor responded by moving his army south to the northern bank of the Rio Grande River, across from Matamoros, Mexico.

The fort was designed by Captain Joseph K. F. Mansfield and made entirely of earth. The walls were 9 feet tall and at least 15 feet thick at the base. The perimeter of the fort was protected by a trench that was 8 feet wide. The fort had six redans — arrow-shaped extensions — that gave it a star shape. Three of the redans faced Matamoros.

The Thornton Affair — the First Engagement of the Mexican-American War

On April 24, Taylor was informed that Mexican troops had crossed the Rio Grande and were headed toward Fort Texas. Taylor responded by sending Captain Seth Thornton and a small force to scout the area, see if they could find the Mexican force, and gather intelligence on it. 

The next day, Thornton and his men were at Rancho de Carricitos, just east of present-day Bluetown, Texas. The Mexicans surrounded them at the ranch and attacked, killing at least 11 Americans and wounding 6. 46 men, including Captain William J. Hardee, were taken as prisoners to Matamoros in the aftermath of the Thornton Affair.

The Mexican Army Approaches Fort Texas

On May 1, 1846, General Arista crossed the Rio Grande to place his forces between Taylor’s army at Fort Texas and the American supply base at Point Isabel. Taylor left to secure his supply line and placed Major Jacob Brown in command of Fort Texas.

Siege of Fort Texas, View of the Fort, 1846
This illustration depicts Fort Brown in 1846. Image Source: The Mexican War and Its Warriors, 1848.

The Siege of Fort Texas Starts on May 3, 1846

Arista sent a force under General Pedro de Ampudia to lay siege to the fort. Around 5:00 a.m. on May 3, the Mexican batteries opened fire, firing approximately 1,500 rounds against the fort in the first 24 hours and 3,000 over the course of six days.

Brown responded to the bombardment by pointing some of the fort’s guns toward Matamoros and firing into the city. Despite the bombardment, the fort held. As the days went by, the Mexicans reduced the number of shots fired at the fort and resorted to a traditional siege. Ampudia may have been waiting for Arista to arrive with reinforcements, which would the Mexicans to launch an assault on the fort.

Brown also ordered his men to save ammunition and only fire when necessary. Brown used the time to make repairs to the fort, while he waited for Taylor to return with reinforcements. On May 6, while Brown was directing repairs to the fort, he was hit by a shell and mortally wounded. He was one of the few casualties of the siege.

Taylor Leaves Point Isabel

On May 7, Taylor left Point Isabel and started his march back to Fort Texas. He had around 2,300 men and more than 200 wagons loaded with supplies. 

Taylor Engages Arista at Palo Alto and Resaca de la Palma

On the way back to Fort Texas, Arista engaged Taylor at the Battle of Palo Alto (May 8). The Americans won the battle, and the Mexicans withdrew that night. Taylor followed Arista and they engaged each other the next day at the Battle of Resaca de la Palma (May 9). Once again, the Americans defeated the Mexicans, sending them back over the Rio Grande into Mexico. 

Battle of Palo Alto, 1846, Taylor Leading Troops
This illustration depicts General Taylor — on his horse — directing troops at the Battle of Palo Alto. Image Source: Library of Congress.

The Siege of Fort Texas Ends on May 9, 1846

With Arista’s defeat, General Pedro de Ampudia was forced to lift the siege and fall back. 

Although the unit surgeon amputated Major Brown’s leg, he succumbed to his wounds and died on May 9, just hours before Taylor’s returned to Fort Texas.

Siege of Fort Texas Outcome

On May 17, 1846, Taylor issued General Order No. 62, renaming the fort as Fort Brown, in honor of Major Brown. As Mexican forces withdrew from Matamoros into the Mexican interior, the threat to Fort Brown ended. 

Siege of Fort Texas — Official Report by Captain Edgar S. Hawkins

In the aftermath of the Siege of Fort Texas, Captain Edgar S. Hawkins wrote an official account of the event and sent it to Assistant Adjutant-General William Wallace Smith Bliss.

Please note that section headings have been added, and text corrections have been made in order to improve understanding of the report. Also, note that Hawkins refers to the fort as “Fort Taylor.” The report is dated May 10 and the fort was renamed Fort Brown on May 17.

Fort Taylor — May 10, 1846

Headquarters, Fort Taylor,

Texas, May 10, 1846.

Sir — I have the honor to report that on the morning of the 6th instant, during the third day of the bombardment of this fort, its gallant commander, Major Brown, received a severe wound, which caused his death at 2 o’clock on the 9th instant. 

Hawkins Takes Command

I immediately assumed command, and have the honor to report the result of the bombardment since 7 o’clock, p.m., on the fourth, at which time Captain Walker left with a report of the result up to that time. At 9 o’clock, p.m., on the fourth, firing of musketry was heard in our rear, about three or four hundred yards distance, and apparently extending a mile up the river, the firing very irregular; this continued until half-past 11 o’clock, p.m. 

The Bombardment Resumes

The garrison was under arms, batteries and defences all manned and continued so during the night. On the fifth instant, at 5 o’clock, a.m., the fire was recommenced from the enemy’s batteries, which was immediately returned from the 18-pounder batter, and 6-pounder howitzer placed in embrasure on the southeast bastion; the firing was kept up one hour, receiving during that time about fifty round shot and shells from the enemy. The batteries on both sides ceased firing at the same time; our expenditure of ammunition was thirty rounds of both caliber. 

The Mexican Withdrawal Begins

At 8 o’clock, a.m., Valdez, a Mexican, came in and reported that a party of dragoons had been driven back from the prairie to the point, and also a party to the fort; that he had seen thirty deserters from Arista’s army, who stated that the Mexicans were without subsistence stores; that they were tired and left for their homes; that it was stated in the Mexican camp that Arista had received an express from Mexico, informing him that another revolution had broken out in Mexico, and that he could receive no support from the government. 

At 9 o’clock, a.m., it was reported that a reconnoissance of officers, escorted by mounted men of the enemy, was going on in rear within eight hundred yards of the fort, and that other parties, mounted and infantry, were at the same distance, extending from the bend of the lagoon to the river. 

Hanson Scouts the Mexican Forces

Lieutenant Hanson, 7th infantry, asked permission to take the dragoons and go and look at them; this was granted, and in an hour he returned, reporting that the enemy was establishing a battery at the cross roads; his appearance among them created great alarm, and they were soon concentrated at a distance under cover of their work. Every man at work to-day strengthening their defences. Several parties of cavalry and infantry seen to-day occupying our old encampment. At 11 o’clock, p.m., musketry was heard in our rear from bend of lagoon to the river. The troops all at their places in the bastions during the night.

Wednesday, May 6 — Brown Wounded

At 5 o’clock, a.m., the cannonade commenced from the lower fort and mortar battery; many round shot and shells thrown until 6 o’clock, when there was a cessation of firing; during the last hour the shot and shells were well directed, bursting in all directions in the interior of the fort, tearing our tents to pieces and injuring several horses. At half past 6 o’clock the signal 18 pounders were fired, at which the enemy opened their batteries in our front and rear, and the cannonade continued from two mortars and a howitzer in front, and a mortar established at or near the cross roads in rear until 10 o’clock, a.m., when our gallant commander received a mortal wound from a falling shell. 

Braxton Bragg’s Artillery Command

Large mounted parties and infantry were seen at this time in rear. At 7 o’clock one mortar was playing upon us from town, and two from the rear. At 10 o’clock, a small party of infantry crept up in ravine and fired musketry, but being out of range the fire was not returned. At half-past 10 o’clock, a.m., several parties of infantry and mounted men were seen surrounding us in rear. Several rounds of canister were fired from Lieutenant Bragg’s battery, which soon dispersed them. 

Braxton Bragg, Portrait
Braxton Bragg during the Civil War. Image Source: Library of Congress.

The Bombardment of Fort Texas Pauses

Several afterwards heard to have been killed. Immediately afterwards, and until half-past 12 o’clock, p.m., we received a continual shower of shells from the enemy’s batteries. At 2 o’clock, five shells were thrown. At half-past 4 o’clock, p.m., a white flag was shown at the old buildings in rear, and a parley sounded by the enemy. Two officers advanced and were met by two officers of my command, who brought me the document marked A, signed by General Arista, allowing me one hour to reply.

The Bombardment of Fort Texas Resumes

This document being considered one of great importance, I deemed it necessary to convoke a council consisting of all the company commanders in my command, and laid it before them: they unanimously concurred with me in the reply, a copy of which is the accompanying document, marked B. This document was despatched in the allotted time, and shortly after its reception the enemy’s batteries opened on us with continual shower of shot and shells until sunset. The night was passed very quietly, but constant vigilance was exercised in the command; every man kept at his post, as an attack was confidently expected in the morning.

Thursday, May 7

At half-past 5 o’clock, a.m., the enemy’s batteries opened with shells, and continued for about an hour and a half, then ceased. At half-past 7, a.m., several rounds of canister and grape were fired into the enemy’s picket-guards, at the houses in rear. and at the old guard-house of the second brigade, which caused them to abandon their positions; this was replied to by a discharge of some ten or twelve shells. 

At 9 o’clock, a.m., we received a shower of some four or five shells, and then stopped. About this time the enemy commenced firing iron shells, having previously thrown composition shells, and it was discovered that one of the mortars had been removed from our rear and returned to the city. 

At quarter-past 10, a.m., we received three shells; at 11, a.m., eight shells; at 12, m., six shells, by which four of Lieutenant Bragg’s horses were killed, and the wheel of one his caissons disabled. At half-past 12 the batteries were opened with round shot and shells, and continued for an hour and a half; by this time our bomb-proofs were so far advanced that our troops were comparatively protected.

At 2 o’clock small parties of infantry commenced on us with random musketry on the bank of the river and from the ravine. At half-past 2, p.m., a regular bombardment with shot and shells from a howitzer and the mortars was kept up with little intermission until sunset. 

At 5 o’clock, during this bombardment, a shell struck in a tent, almost entirely destroying the instruments of the seventh infantry band, to the value of three hundred dollars. The accuracy of their firing now evidently increased, as at least one-half of the shells thrown fell in the fort. A sentinel today lost his arm by a round shot from the enemy. 

As soon as it was dark enough, a party headed by our indefatigable engineer, Captain Mansfield, was sent out to level the traverse thrown up by General Worth, and cutting down the chaparral which served as a cover to the sharpshooters of the enemy. 

At 12 o’clock at night, a random fire of musketry commenced around us, followed by two bugles; this continued for about one hour, and from 3, a.m., was continued until near daylight.

Friday, May 8

At a quarter past five o’clock, a.m., the enemy’s batteries again opened with shells from the lower fort, from the sandbag battery, and from our rear; the fire this morning was kept up until 8 a.m., without cessation. A party was sent out this morning and burned the old houses near the traverse, on the river bank. This drew from them several round shot and shells. 

From twelve to half-past two, p.m., a heavy bombardment of shells was kept up; at least fifty thrown at us during that time. At half-past three they again opened their shells upon us, accompanied by round shot. At this time the enemy had established a mortar in the ridge of chaparral across the river, and immediately west of us. Mortars were now playing upon us from the north, south, and west – four in number. 

The firing of round shot was kept up for two hours, and that of shells until half-past four, when it became very distinct; it lasted until nearly seven, p.m.; this we supposed to be an action between our forces and the enemy. 

A little before sunset a Mexican came running in with a white flag from the direction of the second brigade guard-house, claiming protection; he stated that our forces had come in contact with those of the enemy, had driven them back; that he was a prisoner in charge of the picket guards, fired on by our batteries; and that while they were burying the dead, and carrying off the wounded, he affected his escape. 

During the cannonade, this afternoon a small column of infantry from above, and one of cavalry from below, were seen advancing, supposed to be reinforcements to the enemy. The excitement in our command during this distant cannonading was intense. During the day we received from one hundred and fifty to two hundred shells, and from seventy-five to one hundred round shot, and not a man disabled. 

During the previous night the halyards of the flag on the outside had become unrigged, and, as the firing had become too intense to re-establish them, a temporary staff was erected on the inside, and the national flag of the 7th infantry raised as a substitute. We passed a very quiet night — the troops on the alert at their guns.

Saturday, May 9

An officer of the seventh succeeded in lowering the topmast of the flag-staff and rigging the halyards, but found he could not raise it again without great labor and exposure; he, therefore, lashed it in position, and raised the national flag, after having stood a succession of round shot, canister, and shells from the enemy’s batteries for fifteen or twenty minutes. 

At ten o’clock a sergeant and ten men fired the houses on the road which had been successively occupied by our own and the enemy’s pickets. It brought a heavy discharge of shells, canisters, and round shot, from the enemy’s batteries. Shells, with slight intervals, continued until half-past two, p.m.; the mortar on our west silent, and one firing from a position between us and the fort at the upper ferry; it was much further off, but fired accurately. 

Major Brown Dies

Two, p.m., Major Brown died, and in a short time we heard the re-engagement between the armies.

Mexican Forces Retreat Past Fort Texas

Quarter to six, quite a number of Mexican cavalry and a few infantry were seen in the retreat. At this time we received a heavy fire of round shot and shells from the time the battle commenced, and continued to increase. An eighteen-pounder and six pounder were fired in the direction of the upper ferry, when, finding it difficult to distinguish between friend and foe, the firing was discontinued. 

Praise for Captain Mansfield

I cannot close this report and pass in silence the gallant and laborious efforts of the officers and men of this command to fulfill the high trust imposed in them by the commanding general. Under the most disadvantageous circumstances, labor was performed by the men with the greatest alacrity, and always in good cheer. Our indefatigable engineer, Captain Mansfield, is entitled to the highest praise. We have only to lament the loss of a gallant and faithful officer, who, proud of the trust reposed in him, would have gloried in the accomplishment of the task which he so gallantly commenced.

I have the honor to report, as follows, a list of the killed and wounded during the seven day’s bombardment of Fort Taylor, Texas:

Killed During the Siege of Fort Texas

  • May 3, 1846. Sergeant Weigart, B company, 7th infantry.

Wounded During the Siege of Fort Texas

  • May 6, 1846. Major J. Brown, commanding post.
  • 3, Private Lefear, E company, 3d artillery, slight wound.
  • 6, Private Thompson, E company, 3d artillery, slight wound.
  • 6, Private Thompson, D company, 5th infantry, slight wound.
  • 6, Citizen J. Paugh, sutler’s clerk, slight wound.
  • 7, Mexican prisoner, slight wound.
  • 7, Private Smith, C company, 7th infantry, slight wound.
  • 7, Private Moody, H company, 7th infantry, fracture of arm.
  • 8, Citizen Russell, discharged soldier, fracture of leg.
  • 8, Private Stewart, H company, 7th infantry, slight wound.
  • 8, Private Ratcliff, H company, 7th infantry, slight wound.
  • 8, Mexican prisoner, slight wound.
  • 8, Mexican prisoner, slight wound.
  • 8, Recruit Cowan, 7th infantry, slight wound.

Died During the Siege of Fort Texas

  • May 9, 1846. Major J. Brown, commanding post.

I am, sir, respectfully, your obedient servant,


Captain 7th Infantry, commanding post.

Siege of Fort Texas Significance

The Siege of Fort Texas is important to United States history because it helped secure the Rio Grande River as the southern border of Texas and the United States.

Fort Brown continued to play a key role in the American war effort, with its garrison performing crucial quartermaster functions for Taylor’s Army of Occupation, which became the “Army of Invasion” as it moved south into Mexico. which went on to victory against the Mexican army at Monterrey.

The Siege of Fort Texas was followed by the Battle of Monterrey (September 21–24, 1846).

Citation Information

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  • Article Title The Siege of Fort Texas in 1846
  • Date May 3, 1846–May 9, 1846
  • Author
  • Keywords Siege of Fort Texas, Fort Brown, Mexican-American War
  • Website Name American History Central
  • Access Date May 30, 2024
  • Publisher R.Squared Communications, LLC
  • Original Published Date
  • Date of Last Update October 30, 2023