Conversation so far:
What was the Third Expedition?
In 1845, Carson guided Fremont on their third and last expedition.
What did they do on this expedition?
They went to California and Oregon.
What did they do in California and Oregon?
Once in California, Fremont started to rouse the American settlers into a patriotic fever.
How did he rouse them into a patriotic fever?
CANNOTANSWER.

Question: What else did he do in California?
Self-contained rewrite: What else did Fremont  do in  California, besides starting the rouse with American settlers?