Previous to this time, young Walker had been discharged from the service, by reason of the expiration of his enlistment, and with some funds he had amassed while in the army, proceeded at once to Texas, then embroiled with the abrasions of the great Camanche race and the minor tribes strewn along her northern frontier. He was one of the party of the famous Jack Hays, when in 1844 that leader defeated, with fifteen men armed with Colt's pistols, then novelties in the West, a large force of Indians. In this encounter Walker was wounded by a lance, and left by his adversary pinned to the ground. After remaining in this position for a long time, he was rescued by his companions when the fight was over.
The disastrous expedition commenced under the command of Gen. Somerville, and terminated at Mier by the surrender of the whole party to Don Pedro de Ampudia, since become a person of most unenviable notoriety, is well known. One of the most conspicuous members of this foray, for it scarcely deserves another name, was Walker. He distinguished himself during the long siege the Texans maintained in the house they had seized, until forced for want of provisions and ammunition to surrender. With the rest he was marched to the castle of Perote, suffering every indignity which Mexican cruelty and ingenuity could invent. On this sad march, at Salado, Walker performed perhaps the most brilliant exploit of his life. Wearied out by cruelty, the Texans resolved to escape, and on this occasion Walker was the leader. The prisoners were placed in a strong stone building, at the door of which two sentinels were placed, while their escort bivoucked in front of the building. Walker, at a concerted signal, threw open the door, seized and disarmed one of the sentinels, while a gallant fellow named Cameron, a Highlander, was equally successful with the other. The unarmed prisoners immediately rushed through the gateway and seized the arms of the Mexican guard. No scheme was ever more daringly planned or more boldly executed. Within the course of a moment the two hundred and fourteen Texans had changed places with the numerous Mexican guard. Outside of a court-yard, in which the guard had bivoucked, was a strong cavalry force, which the Texans charged with the bayonet and routed, and immediately resumed their march back to the Rio Grande.