Conversation so far:
What was Orson Welles' first project in radio?
In addition to being a repertory player on The March of Time, in the fall of 1936 Orson Welles adapted and performed Hamlet on CBS Radio's Columbia Workshop.
How much did Orson Welles make while doing radio?
Between 1935 and 1937 Orson Welles was earning as much as $2,000 a week, shuttling between radio studios at such a pace that he would arrive barely in time.
Which studios did Orson Welles perform for?
Orson Welles worked for CBS radio as well as The Mutual Network.
What was the name of one show Orson Welles did?
Orson Welles created and sponsored The Mercury Wonder Show for Service Men. It was a magic-and-variety stage show by Mercury Theatre for US soldiers in World War II.
Which show was Orson Welles most famous for?
Orson Welles' radio series gave the platform to find international fame as the director and narrator of a radio adaptation of H. G. Wells's novel The War of the Worlds.

Question: Why was that show so important?
Self-contained rewrite: Why was The Mercury Theatre series so important?