On this date in 1953, Jackie Cochran became the first woman to break the sound barrier. R.I.P., Colonel. https://en.m.wikipedia.org/wiki/Jacqueline_Cochran
Being the first female to break the speed of sound may not be a big deal, along the lines of that being done before and it's just a record. That according to some sources she had more overall speed/altitude records set than anyone else, male or female, is probably a big deal. That she was one of the pioneers in getting women's air corp up and running, to do test and ferry flights of combat aircraft in WW2 was absolutely a big deal. Those flight materially helped the war, and were not done without significant risk.