Augustus Magee, a Louisiana-based U.S. army officer, had befriended Mexican patriot Bernardo Gutierrez, who is fighting for Mexican independence from Spain.

The two had led an expedition into Texas and captured Nacogdoches and Goliad and before Magee dies mysteriously in Goliad in February.

The Republican Army of the North, composed of Anglo-Americans, Mexicans and natives, along with some help from the United States, had crossed over from Louisiana into Texas.

Flying a green flag, they had captured the town of Nacogdoches on August 7, 1812.

The Republican Army of the North had then marched to Goliad, where they had captured Presidio La Bahia.

From November 13, 1812, to February 19, 1813, they had been besieged, when the Royalist Army,  commanded by Manuel María de Salcedo, the Governor of Texas, and Simón de Herrera, the Governor of Nuevo León, had gathered to confront them.

Unable to defeat the Republican Army, they had retreated back to San Antonio.

Samuel Kemper, who had also been involved in the 1804 rebellion in Florida, had become the commander after the death of Colonel Magee.

The Republican Army, now numbering about nine hundred men, pursues.

On March 29, 1813, the Royalist force, numbering fifteen hundred men, plans to ambush the Republican Army from a ridge overlooking Rosillo Creek, approximately nine miles southeast of San Antonio de Bexar near the confluence of Rosillo Creek and Salado Creek.

Their trap fails when they are detected by the Republican forces, who defeat them in less than an hour.

At a cost of six men, the Republican Army kills one hundred to three hundred and thirty Royalist soldiers and captures materiel including six cannon and fifteen hundred horses.

The Royalists had retreated to San Antonio, where they surrendered to the Republican Army on April 1.

Two days later Salcedo, Herrera, and twelve others were executed by the victors.

On April 6, the Republican Army issues a draft declaration of independence.