The Battle of San Patricio was fought on February 27, 1836, between Texian rebels and the Mexican army, during the Texas Revolution.

Unbeknownst to the Texians, on February 18 Mexican General José de Urrea had led a large contingent of troops from Matamoros into Texas.

The Texian immigrants refused to comply with Mexico's new bans on slavery, and described Santa Anna's attempts to free their slaves as "piratical attacks" to take their "property".

[9] Determined to quash the rebellion, Santa Anna began assembling a large force to restore order; by the end of 1835, his army numbered 6,019 soldiers.

Many left the army, while others joined the troops stationed under Houston's second-in-command, James Fannin, at Presidio La Bahia in Goliad.

[19] Despite hearing rumors that the Mexican army was approaching, Grant and Johnson chose to take their men south of the Nueces River, into territory belonging to the state of Tamaulipas, to search for horses to buy, steal, or otherwise gather.

[20] Johnson's men arrived on February 24 in San Patricio, an Irish settlement about 100 miles (160 km) north of Matamoros.

[21] Johnson sent twelve men to guard the horses at the ranch of Julian de la Garza, approximately 4 miles (6.4 km) outside the town, while the rest garrisoned in San Patricio.

Confident that Grant would alert him if Mexican troops were in the area, Johnson chose not to appoint sentries, instead allowing all of the men to take shelter.

[24] Urrea instructed three officers to go to San Patricio dressed as civilians and warn the centralists that the Mexican army was approaching.

In an effort to reduce casualties and property damage, centralists were asked to declare their loyalties by leaving lanterns burning in their windows.

[25] Urrea sent 30 men under Captain Rafael Pretalia to de la Garza's ranch to surprise the Texians camped there.

Determined to prevent more casualties, Mexican dragoons prepared to set the house on fire to force the Texians out.

[26] By chance, Johnson and three of his men, Lieutenant Daniel Toler and Sergeants Love and Miller, were still awake and discussing tactics.

Mexican troops had been told that the house where Johnson was quartered was one of their targets, yet a lamp burned in the window, signaling that this was the home of a loyalist.

In the subsequent fight, four Texians died, eight men (three Americans and five Tejanos, Mexican-Ethnicity Texans) were taken prisoner, and several escaped.

[22] They made their way on foot to Refugio, where they sent a messenger to Fannin at Goliad, 75 miles (121 km) north, to let him know that Urrea's army was close.

[28] While Urrea waited for reinforcements before beginning his march towards Goliad, his advance party searched for Grant and the remaining Texians.

[32] After learning of Grant's whereabouts from local spies, on March 2 Mexican dragoons ambushed the Texians at Agua Dulce Creek.