Conversation so far:
What happened with Sarah Vaughan in 1943?
During her week of performances at the Apollo, Sarah Vaughan was introduced to bandleader and pianist Earl Hines. After a brief tryout, Hines replaced his female singer with Vaughan.
How did Hines replacing his female singer with Sarah Vaughan turn out?
Sarah Vaughan spent the remainder of 1943 and part of 1944 touring the country with the Earl Hines big band.
Did Sarah Vaughan develop her musicianship?
Sarah Vaughan was hired as a pianist so Hines could hire her under the jurisdiction of the musicians' union. After Cliff Smalls joined, her duties were limited to singing.

Question: What is the most important fact listed in this article?
Self-contained rewrite: What is the most important fact listed in the Sarah Vaughan article?