Lt. Nyota Uhura was the communications officer on the original Enterprise in the first series of Star Trek, and went on to reprise her role in several subsequent films. However, an answer in this question states that she once also held the rank of Captain.
When did this happen, and under what circumstances? Futhermore, did it have any lasting impact?
I am aware that Uhura's presence as an officer on the Enterprise was already groundbreaking, given the social situation in the United States at the time.