On October 13, the newly created Texian Army under Stephen F. Austin had marched towards Bexar, where General Martín Perfecto de Cos commanded the remaining Mexican soldiers in Texas.

On October 27, Austin sent Bowie and Fannin, with 90 soldiers, to find a defensible spot near Bexar for the Texian Army to rest.

The newly organized Texian Army, determined to put a decisive end to Mexican control over Texas, began marching towards San Antonio de Bexar on October 13, 1835.

[3] By October 20 the Texians—led by Stephen F. Austin, the first empresario to bring English-speaking settlers to Texas[Note 1]—had reached Salado Creek and initiated a siege of Béxar.

[9] The rest of the Texian Army joined them there early Bowie and Fannin were accompanied by ninety soldiers, divided into four companies led by Captains Andrew Briscoe, Robert Coleman, Michael Goheen, and Valentine Bennet.

[13] According to historian Alwyn Barr, "trees shaded both sides of the broad river bottom which lay about six feet below the level of the rolling praire [sic?]

[12][15] Heavy fog delayed their approach, and the Mexican soldiers did not reach Concepción until 14:00 or 8:00 a.m.[15] A Mexican cavalry scout fired at Texian picket Henry Karnes; after returning fire, Karnes ran back to his company, frustrated because, as he put it, "Boys, the scoundrels have shot off my powder horn".

In response, Texians trimmed undergrowth near their camp to provide better visibility and dug steps into the embankment so that they could more easily climb up to fire.

[15] According to Texian Noah Smithwick, "grapeshot and canister thrashed through the pecan trees overhead, raining a shower of ripe nuts down on us, and I saw men picking them up and eating them with as little concern as if they were being shaken down by a norther.

"[13] In his official report to Austin, Bowie remarked that "The discharge from the enemy was one continued blaze of fire, whilst that from our lines, was more slowly delivered, but with good aim and deadly effect.

"[16] When Mexican officers ordered a charge on the south bend held by Fannin, Bowie sent Coleman's company to help.

[18] As the reinforcements reached the southern part of the horseshoe, the Mexican infantry fell back, leaving the cannon within 100 yards (91 m) of the Texians.

[17] Austin had intended to reunite the two parts of his army early on October 28, but the group camping at Mission Espada had delayed their departure to unsuccessfully pursue a company that had deserted.

[17] Lieutenant Colonel William Barret Travis and his company of cavalry rode ahead of the main body of the army.

[18] That evening, Austin allowed a local priest and men from Bexar to retrieve the bodies of the Mexican soldiers who had died in battle.

[22] This battle, which historian J. R. Edmondson describes as "the first major engagement of the Texas Revolution",[1] was the last offensive against the Texians that Cos would order.

[22] Although Barr continues that the battle "should have taught ... lessons on Mexican courage and the value of a good defensive position",[24] Hardin believes that "the relative ease of the victory at Concepción instilled in the Texians a reliance on their long rifles and a contempt for their enemies".