Conversation so far:
When did Jo Stafford sign with Capitol Records?
Jo Stafford subsequently became the first solo artist signed to Capitol after leaving the Pied Pipers in 1944.
Was was the USO group Jo Stafford was working with?
Jo Stafford's tenure with the United Service Organizations during World War II, which often had her perform for soldiers stationed in the U.S., earned her the nickname G.I. Jo

Question: What role did she play?
Self-contained rewrite: What role did Jo Stafford play with the USO?