Deep Purple performed on this day in 1971 at the Auditorium Theater in Chicago, Illinois.
Purple were at this time apparently just finishing up their legendary In Rock World Tour. As a grand finale, they were apparently going to tour the United States. Their support act for this and other nights early in this leg was Fleetwood Mac. This was the third concert of this leg of the tour, which was also the third leg in North America of the In Rock Tour.
However, this concert turned out to be the last concert on this leg of the tour, and indeed of the tour as a whole. Singer Ian Gillan collapsed early in the concert and was rushed to the hospital, where he was diagnosed with hepatitis. This forced the cancellation of the tour while he returned home to England to recuperate. He would rejoin the rest of the group later that year in Montreux for some fire-related excitement and to work on their next album.
Despite the fact that this concert was interrupted by Gillan’s medical emergency, it actually continued. The group performed a mostly-instrumental night, building on their already instrumental-heavy performances typical of the era. Bassist Roger Glover also apparently filled in on vocals for at least one number. At a portion of one concert, Glover’s technical tenure as Deep Purple’s lead singer is the shortest of anyone who sang lead with the band.
There is (regrettably) no known recording of this particular concert.