Thornton Affair

Thornton Ambush
Part of the Mexican–American War
Rancho de Carricitos
Date 25 April 1846 Location Near Brownsville, Texas Result Mexican victory Start of the Mexican–American War
Belligerents
United States	Mexico
Commanders and leaders
Seth Thornton William J. Hardee	Anastasio Torrejón
Strength
80 cavalry	1600 cavalry, sappers, light infantry
Casualties and losses
11 killed 6 wounded 49 captured	unknown

Mexican victory

Seth Thornton

The Thornton Affair, also known as the Thornton Skirmish, Thornton's Defeat, or Rancho Carricitos was a battle in 1846 between the military forces of the United States and Mexico twenty miles west upriver from Zachary Taylor's camp along the Rio Grande. The much larger Mexican force defeated the Americans in the opening of hostilities, and was the primary justification for U.S. President James K. Polk's call to Congress to declare war.

Although the United States had annexed Texas, both the US and Mexico claimed the area between the Nueces River and the Rio Grande. Polk had ordered Taylor's Army of Occupation to the Rio Grande early in 1846 soon after Mexican President Mariano Paredes declared in his inaugural address to uphold the integrity of Mexican territory to the Sabine River.

Mariano Arista assumed command of the Division of the North on 4 April and arrived at Matamoros on 24 April, making the total force there about 5000 men, and notified Taylor hostilities had commenced. Arista promptly ordered General Anastasio Torrejon to cross the Rio Grande fourteen miles upstream at La Palangana.

Taylor received two reports on 24 April of Mexicans crossing the Rio Grande, the first crossing below his camp, the other a crossing upriver. Taylor ordered Captain Croghan Ker to investigate downriver and Captain Seth B. Thornton with two Dragoon companies to investigate upriver. Ker found nothing but Thornton rode into an ambush and his 80-man force was quickly overwhelmed by Torrejon's 1600, resulting in the capture of those not immediately killed. Thornton's guide brought news of the hostilities to Taylor and was followed by a cart from Torrejon containing the six wounded, Torrejon stating he could not care for them.

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