In 1844, he brought a party of immigrants including his father David and brother Samuel from Oregon on the Siskiyou Trail to Sutter's Fort.

He also served with his brothers in the California Battalion under Col. John C. Fremont and were honorably discharged in Los Angeles or San Gabriel in the early part of 1847.

The Pomo workers, forced to camp near a hostile group of local Indians and suffering from malaria and starvation, were left on their own.

Following the murder of his brother Andrew in 1850, Benjamin Kelsey seems to have joined a vigilante group that killed an unknown number of Indians.

[3] After recovering from malaria, Ben used his profits to buy sheep which he drove to the mines and used that money to set up a trading post in the Sacramento Valley but lost his investment when he became ill.

[4] Suspicion may have fallen on him because his brother Samuel had been accused of being a leader among the secessionists in San Bernardino at the start of the American Civil War.