In August he was promoted to captain and assigned to command of Company B. Sam Houston appointed him an ambassador to the Shawnee Indians on January 24, 1837, to sound out the tribe's intentions towards the Republic of Texas and Mexico.

[2] In January 1843 Snively proposed an operation to intercept a train of Mexican traders who would be returning from Missouri on the Santa Fe Trail by way of Texas territory and to seize their goods.

Leaving on April 24, this 170-man strong Battalion of Invincibles fought and defeated a detachment of 100 Mexican soldiers on the Arkansas River on June 20.

However, on July 15, they were in turn surrounded and disarmed by a detachment of the U. S. Dragoons under the command of Captain Philip St. George Cooke for intruding into U. S. territory and killing a Mexican citizen.

There he led a group that discovered gold placers on the Gila River twenty miles east of Fort Yuma.

From 1866 Snively's affairs prospered with the success of the Castle Dome mine and as he made and lost small fortunes in New Mexico and Nevada ventures.