Which militia group did Samuel Clemens join at the beginning of the Civil War?

At the beginning of the American Civil War, Samuel Clemens joined a pro-secessionist militia group known as the Marion Rangers.1

This group consisted of approximately a dozen men and remained active for only two weeks, during which they primarily retreated from rumors of Union troops before disbanding. Clemens later reflected on this brief and uneventful military experience in his memoir, The Private History of the Campaign That Failed (1885), where he humorously noted that he was not suited for soldiering. Following the dissolution of the unit, Clemens traveled to the Nevada Territory with his brother, Orion.1