Just got off the phone with Angus Wynne (created Texas International Pop Festival with Janis Joplin, Led Zepplin, Jimi Hendrix and others).
He had Ike and Tina booked at Soul City, their last gig together. For those that think Tina was a wallflower, he really blows a hole in that way of thinking. All three of them were backstage, Ike was about to go onstage when Tina backhanded him to start the fight, Ike responded with a punch to her face. After Ike came off, Tina went onstage to do her set with a towel so she could wipe the blood off her mouth. Angus said that Tina started at least half the fights. When they got back to the hotel is when Tina took off