[1] Democratic Senator Thomas Hart Benton of Missouri was a prominent leader of this movement, into which he enlisted his son-in-law, John C. Frémont.
[2][3] Upon arriving in California, Frémont and his men moved about the northern half of the state for several months, provoking the Mexican authorities and building up patriotic sentiment among Americans who had settled there.
In his memoirs, expedition member Thomas S. Martin stated, "We followed up the Sacramento River killing plenty of game, and an occasional Indian.
"[6] On the night of 9 May 1846, a band of 15–20 Klamath natives retaliated and attacked Frémont's group under cover of darkness, killing 2–3 members of the party.
John C. Frémont and his band continued to kill Native Americans on sight on the way back down to California and committed a "preemptive" attack on a rancheria, known as the Sutter Buttes massacre.
The Klamath people continued to be subject to violence from White settlers, including a long string of similar massacres and attacks.
In 1954 an Act of Congress terminated the tribal status of the Klamath, forcing them to give up their claim to the land and lose all federal services in exchange for a monetary payoff.