Morton to provide ether anesthesia while Warren performed a minor surgical procedure.

In 1799, he continued his medical studies in London and Paris and Edinburgh, including work with the pioneer anatomist Sir Astley Cooper (1768–1841).

[4][5] Upon his return to America in 1802, Warren entered into partnership with his father and also assisted him with anatomical lectures, dissections, and demonstrations at Harvard Medical School.

Warren was the first dean of Harvard Medical School (1816–1819) and promoted its move from Cambridge to Boston.

[8] Over the course of his long career, Warren assembled an extraordinary teaching collection of anatomical and pathological specimens, which he presented to Harvard in 1847 along with $5000.

Although Warren did not believe that the anesthesia would work, he arranged for a demonstration at Massachusetts General Hospital.

Warren presented Wells to his students but the patient who had been scheduled that morning, for an amputation, refused to be operated on.

In fact, Warren wrote that he forgot that this operation even happened, as he was "very much occupied at the time" and didn't recall it until Wells himself mentioned it in 1847.

[11] His personal journal for this day records, "Did an interesting operation at the Hospital this morning, while the patient was under the influence of Dr. Morton's preparation to prevent pain.

Mindful of the potential importance of the demonstration, Warren invited noted photographers Southworth & Hawes to document the surgery via a re-enactment.

[12] It was believed for over 100 years that his remains laid in his memorial tomb at Forest Hills Cemetery in Jamaica Plain, MA but in fact his remains are divided; his skeleton is in a coffin-like box at Harvard's Warren Museum, since he donated his body to Harvard Medical School for research, and his so-called "morbid parts" [i.e. flesh] only were interred in the tomb.