Conversation so far:
What military branch did Joseph McCarthy join?
Shortly after the U.S. entered World War II, Joseph McCarthy joined the United States Marine Corps.
What other career did Joseph McCarthy have besides the Marine Corp in the military?
Joseph McCarthy was admitted to the bar in 1935.

Question: What did he do at the law firm?
Self-contained rewrite: What did Joseph McCarthy do at the law firm in Shawano, Wisconsin?