Conversation so far:
What was the Third Expedition for Kit Carson?
In 1845, Carson guided Frémont on their third and last expedition.
What did Kit Carson and John Charles Frémont do on their third expedition?
They went to California and Oregon. Frémont made scientific plans, but the expedition appeared to be political in nature.
What did Kit Carson and John Charles Frémont do in California and Oregon?
President Polk wanted the province of Alta California for the United States. Once in California, Frémont started to rouse the American settlers into a patriotic fervor.

Question: How did he rouse them into a patriotic fervor?
Self-contained rewrite: How did John Charles Frémont rouse American settlers into a patriotic fervor in California?