"It's a story of how medicine changed the course of civilisation," said Mark C Preul, chair of neurosurgery research director at Barrow Neurological Institute, which is part of Dignity Health St Joseph's Hospital and Medical Center in the US.
For more than two centuries, history has focused on Kutuzov's incredible story, researchers said.
He survived being shot in the head in 1774 and 1788 and went on to become one of Russia's legendary heroes by repelling Napoleon's invaders.
"We wanted to find out what really happened and basically identify this surgeon who saved Mikhail Kutuzov," Preul said.
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"Massot's facts were somewhat buried. He is at the vanguard of surgical technique. He uses incredibly modern techniques that we still use today," he said.
What researchers found was evidence that the first bullet wound, sustained in a battle with the Turks in Crimea in 1774, had destroyed Kutuzov's frontal lobe.
Kutuzov's injury most likely impaired his ability to make decisions. Eye witnesseses remark about his altered personality after the first gun shot wound.
So instead of challenging Napoleon's superior forces in the autumn of 1812, Kutuzov put off a confrontation. He ordered Moscow burned and fled with his army to safety east of Moscow.
Napoleon's army pursued, invading Moscow, but lacking food and supplies, succumbed to a horribly brutal early Russian winter. Napoleon abandoned the army in December and returned to Paris in defeat.
"However ironically the healing resolution of this situation allowed him to make what turned out to be the best decision. If he had not been injured, he may well have challenged Napoleon and been defeated," Preul said.
"Although some would say fate allowed the brilliant Russian general, who became the personification of Russian spirit and character, to survive two nearly mortal head wounds, the best neurosurgical technique of the day seems to have been overlooked as a considerable part of Kutuzov's success," the researchers said.