Chuck Yeager famously broke through the sound barrier on October 14, 1947; for more on that story check out this old article from Vintage Space.
So it made sense that Yeager wanted to be the first to hit the next speed milestone of Mach 2, but he wasn't the only contender. It was a battle between Yeager flying for the Air Force and Scott Crossfield flying for the NACA (the National Advisory Committee for Aeronautics) but with US Navy stamped on the program. Crossfield won, but Yeager beat his record less than three weeks later. But it didn't totally matter: Crossfield was the first man to fly Mach 2.
I get into that story in my book, Breaking the Chains of Gravity, which is coming out on October 22 in the UK and January 12 in the US and Canada... and Australia and India at that point I think, too! (Pre)Order it on Amazon.
And there's a lot more space history on the blog.
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