The Mier expedition was an unsuccessful military operation launched in November 1842 by a Texian militia against Mexican border settlements; it was related to the Somervell expedition. It included a major battle at Ciudad Mier on December 26 and 27, 1842, which the Mexicans won. The Texian attack was launched partly in hopes of financial gain and partly in retaliation for the Dawson Massacre earlier that year, in which thirty-six Texas militia were killed by the Mexican Army. Both conflicts were part of continuing efforts by each side to control the land between the Rio Grande and Nueces River. The Republic of Texas believed that the territory had been ceded to it in the Treaties of Velasco by which it gained independence, but Mexico did not agree. The expedition is best known for the Black Bean Episode, in which the Mexican Army decimated escaped prisoners, selecting for execution one in ten prisoners by drawing beans from a pot.

Samuel Hamilton Walker was an American army officer. He served as a Texas Ranger captain and officer of the Republic of Texas and the United States armies. Walker served in several armed conflicts, including the American Indian Wars and the Mexican–American War.