Task: Question Answering
Input (English): Passage: While Stafford was still working for Dorsey, Johnny Mercer told her, "Some day I'm going to have my own record company, and you're going to record for me." She subsequently became the first solo artist signed to Capitol after leaving the Pied Pipers in 1944. A key figure in helping Stafford to develop her solo career was Mike Nidorf, an agent who first heard her as a member of the Pied Pipers while he was serving as a Captain with the United States Army. Having previously discovered artists such as Glenn Miller, Artie Shaw, and Woody Herman, Nidorf was impressed by Stafford's voice, and contacted her when he was demobilized in 1944. After she agreed to let him represent her, he encouraged her to reduce her weight and arranged a string of engagements that raised her profile, and confidence.The success of Stafford's solo career led to a demand for personal appearances, and from February 1945 she embarked on a six-month residency at New York's La Martinique nightclub. Her performance was well-received—an article in the July 1945 edition of Band Leaders magazine described it as "sensational"—but Stafford did not enjoy singing before live audiences, and it was the only nightclub venue she ever played. Speaking about her discomfort with live performances, Stafford told a 1996 interview with The New Yorker's Nancy Franklin, "I'm basically a singer, period, and I think I'm really lousy up in front of an audience—it's just not me."Stafford's tenure with the United Service Organizations (USO) during World War II—which often saw her perform for soldiers stationed in the U.S.—led to her acquiring the nickname "G.I. Jo". On returning from the Pacific theater, a veteran told Stafford that the Japanese would play her records on loudspeakers in an attempt to make the U.S. troops homesick enough to surrender. She replied personally to all the letters she received from servicemen. Stafford was a favorite of many servicemen during both World War II and the Korean War; her recordings received extensive airplay on the American Forces radio and in some military hospitals at lights-out. Stafford's involvement with servicemen led to an interest in military history and a sound knowledge of it. Years after World War II, Stafford was a guest at a dinner party with a retired naval officer. When the discussion turned to a wartime action off Mindanao, the officer tried to correct Stafford, who held to her point. He countered her by saying, "Madame, I was there". A few days after the party, Stafford received a note of apology from him, saying he had re-read his logs and that she was correct. 
Question: What nickname was given to Stafford?
Output (English): G.I. Jo.