Conversation so far:
When did Joseph McCarthy join the military?
In 1942, shortly after the U.S. entered World War II, Joseph McCarthy joined the United States Marine Corps.
What did Joseph McCarthy do in the Marine Corps around World War II?
Joseph McCarthy served as an intelligence briefing officer for 30 months.

Question: What did he oversee as the briefing officer ?
Self-contained rewrite: What did Joseph McCarthy oversee as the intelligence briefing officer?