Some three hundred and eight Texan soldiers, who had ignored orders to pull back from the Rio Grande to Gonzales, approach Ciudad Mier.

They camp on the Texas side of the Rio Grande.

Seven hundred soldiers participate in the capture of the town, while the others remain behind as the camp guard.

The Texans are unaware that  three thousand Mexican troops are in the area under the command of generals Francisco Mexia and Pedro de Ampudia.

In the Battle of Mier that results, the Texians are outnumbered ten to one.

They inflict heavy casualties on the Mexicans—six hundred and fifty dead and two hundred wounded—but they are forced to surrender on December 26.

The Mexicans took 243 Texans as prisoner and marched them toward Mexico City via Matamoros, Tamaulipas, and Monterrey, Nuevo León

The Texian prisoners reach Saltillo, Coahuila, to learn that an outraged Santa Anna had ordered all the escapees to be executed, but General and Governor Francisco Mexía of the state of Coahuila had refused to follow the order.

The new commander, Colonel Domingo Huerta, moves the prisoners to El Rancho Salado.

By this time, diplomatic efforts on behalf of Texas by the foreign ministers of the United States and Great Britain have led Santa Anna to compromise: he says one in ten of the prisoners will be killed.

Officers and enlisted men, in alphabetical order, are blindfolded and ordered to draw beans.

The seventeen men who draw black beans are allowed to write letters home before being executed by firing squad on March 25, 1843.

Taylor, his logistics in order by August, had begun his advance on Monterrey, traveling through the virtual Federalist stronghold that is northern Mexico and receiving increasing support from the anti-Centralist rebels.

Taylor’s force reaches the fortified town in September 19, 1846, and attacks the more than ten thousand-man garrison two days later.

The hard-fought Battle of Monterrey results in serious losses on both sides.

The American light artillery is ineffective against the stone fortifications of the city.

The Mexican forces are under General Pedro de Ampudia and repulse Taylor's best infantry division at Fort Teneria.

After the twenty thousand men under General William J. Worth capture the road between Saltillo and Monterrey, Worth sends six companies of Texas rangers up Federation Hill as a diversionary force attacks the town from the opposite side of the city.

The Rangers seize the Mexican artillery and turn it on the retreating enemy forces.

American soldiers, including many West Pointers, have never engaged in urban warfare and they march straight down the open streets, where they are annihilated by Mexican defenders well-hidden in Monterrey's thick adobe homes.

After two days, they change their urban warfare tactics.

Texan soldiers have fought in a Mexican city before (the Siege of Béxar in December 1835) and advise Taylor's generals that the Americans need  to "mouse hole" through the city's homes.

In other words, they need to punch holes in the side or roofs of the homes and fight hand to hand inside the structures.

Mexicans call the Texas soldiers the Diabólicos Tejanos (the Devil Texans).

This method proves successful.

Eventually, these actions drive and trap Ampudia's men into the city's central plaza, where howitzer shelling forces Ampudia to negotiate a truce.

Taylor agrees to allow the Mexican Army to evacuate and to an eight-week armistice in return for the surrender of the city.

Taylor, roundly criticized by the military and Polk for agreeing to the armistice, informs Santa Anna that he will terminate the armistice early.

Taylor’s force occupies Saltillo, southwest of Monterrey, on November 16, 1846.

Santa Anna blames the loss of Monterrey and Saltillo on Ampudia and demotes him to command a small artillery battalion.

General Zachary Taylor receives word on February 21 of Santa Anna’s advance.

His forty-six hundred men men outnumbered three to one, he takes up a position a few miles from Saltillo at at a mountain pass called Buena Vista.

Santa Anna suffers desertions on the way north and arrives with fifteen thousand men in a tired state.

He demands and is refused surrender of the U.S. Army; he attacks the next morning.

Santa Anna flanks the U.S. positions by sending his cavalry and some of his infantry up the steep terrain that makes up one side of the pass, while a division of infantry attacks frontally along the road leading to Buena Vista.

Furious fighting ensues, during which the U.S. troops are nearly routed, but manage to cling to their entrenched position, thanks to the Mississippi Rifles, a volunteer regiment led by Jefferson Davis, who forms them into a defensive V formation.

The Mexicans have inflicted considerable losses but Santa Anna, having received gotten word of upheaval in Mexico City, withdraws in the night, leaving Taylor in control of part of Northern Mexico.