Video: 'The Mexican American War - How Did it Start?'

(Saturday, April 25, 1846, morning local time; during the Mexican-American War) — The Mexican-American War began today when more than 1,000-strong Mexican cavalry detachment attacked a 63-man U.S. patrol under the command of Captain Seth Thornton, which had been sent into the contested territory north of the Rio Grande and south of the Nueces River.

Video: 'U S History Thornton Affair Mr. Ramaker'

In the Thornton Affair, the Mexican cavalry routed the patrol, killing 11 American soldiers.