Conversation so far:
How did Andy Griffith get Andy Griffith's start as a comedian?
Griffith's early career was as a monologist, delivering long stories such as What It Was, Was Football, which is told from the point of view of a naive country preacher.
When did he start acting?
Griffith starred in Ira Levin's one-hour teleplay version of No Time for Sergeants (March 1955) -.
What was his role in that teleplay?
-- a story about a country boy in the United States Air Force -- on The United States Steel Hour, a television anthology series.

Question: How did he transition into comedy from his monoloques?
Self-contained rewrite: How did Andy Griffith transition into comedy from his monoloques?