Mike Jay at the Boston Globe had what appeared to be a pretty compelling lookback piece on Sunday, June 7. It started as follows:

The day pain died
What really happened during the most famous moment in Boston medicine

The date of the first operation under anesthetic, Oct. 16, 1846, ranks among the most iconic in the history of medicine. It was the moment when Boston, and indeed the United States, first emerged as a world-class center of medical innovation. The room at the heart of Massachusetts General Hospital where the operation took place has been known ever since as the Ether Dome, and the word "anesthesia" itself was coined by the Boston physician and poet Oliver Wendell Holmes to denote the strange new state of suspended consciousness that the city's physicians had witnessed. The news from Boston swept around the world, and it was recognized within weeks as a moment that had changed medicine forever.

Wow. Pretty bracing stuff, except for one thing: A commenter named "introp" told the Globe (currently the fourth comment down) that they're wrong about Morton being first.

The evidence is on the side of "introp."