Conversation so far:
What was Edward Canby's final assighnment?
In August 1872, Edward Canby was posted to command the Pacific Northwest.
What did Edward Canby experience in the Pacific Northwest?
In August 1872, Edward Canby was posted to command the Pacific Northwest. He soon faced problems with the Modoc tribe, who had traditionally lived in Northern California.
How did Edward Canby die?
Captain Jack shot Edward Canby twice in the head and cut his throat.

Question: Who was Captain Jack?
Self-contained rewrite: Who was Captain Jack?