The expedition departed San Antonio on November 25. It captured Laredo on December 8. They then headed south along the Rio Grande and soon afterward took the town of Guerreo.

Houston's instructions to Somervell were to continue the invasion only if circumstances assured a reasonable chance for success. Because almost one-third of the participants returned home soon after the capture of Laredo, Somervell determined that the remaining force was not strong enough nor did they have the supplies and equipment to successfully sustain further penetration into Mexico. He therefore ordered his men to disband and return to Texas.

A large number of the Texans, however, felt betrayed by the order. They elected to ignore Somervell and continue the raid into Mexico. Thus, over 300 of the men elected to continue the raids in what came to be known as the Mier Expedition.