On July 24, 1861 Lieut. Col. John Robert Baylor let 300 men consisting of two companies and the second Texas mountain rifles, a Texas light artillery company without it's howitzers in El Paso County scout company, and some civilians from Fort Bliss to Fort Fillmore, New Mexico Territory.

The Texans reached the vicinity of Fort Fillmore at night and placed themselves between the fort and it's water supply at the river. Baylor canceled I planned attack after learning that one of his men had warned the garrison. His Texans forded the Rio Grande and early that afternoon entered nearby Mesilla, and strongly pro-Confederate community. With 380 infantry and hunted rifleman, plus howitzers, Union major Isaac Lynde, approached the Mesilla from the south on July 25. Baylor rejected his demand for surrender. Lyne ordered a return to the fort. The Confederates remained in Mesilla, fearing a trap. Baylor sent to El Paso for artillery and additional men. When Lynde found out that Baylor had sent for artillery, he ordered Fort Fillmore abandoned that night. Because Baylor blocked the shortest retreat route, north up the Rio Grande toward Fort Craig, Lynde and his troops headed northeast toward San Augustine Pass in the Organ Mountains with the objective to reach Fort Stanton, 150 miles away.

At sunrise on July 27, Baylor discovered Lynde’s withdrawal. Baylor’s troops and some “Arizona” civilians gave chase. By the time Baylor’s speediest horsemen caught up with the stragglers, the roadside was littered with discarded equipment and prostrate regulars begging for water. Lyne and his mounted troops reached San Augustine Springs, and attempted to send water back to the lagging infantry. Baylor with part of his command crossed the mountains by another pass and early in the afternoon of July 27, rode unopposed into Lynde’s temporary camp. After a short discussion, Lynde surrendered his 492-man force. The victory as Mesilla was one of the war’s early and surprising Confederate successes.

On August 1, Baylor proclaimed the Arizona Territory, Confederate States of America, and named himself governor. Mesilla remained the capital of the Confederate Arizona Territory until the Texan military forces withdrew back to Texas in July 1862. Baylor’s dashing actions of the summer of 1861 added to his fame as a folk hero.