Cause of death

Napoleon's physician, François Carlo Antommarchi, led the autopsy which found the cause of death to be stomach cancer, though he did not sign the official report. Napoleon's father had died of stomach cancer though this was seemingly unknown at the time of the autopsy. Antommarchi found evidence of a stomach ulcer, and it was the most convenient explanation for the British who wanted to avoid criticism over their care of the emperor.

Napoléon sur son lit de mort [Napoleon on his death bed], by Horace Vernet, 1826

In 1955, the diaries of Napoleon's valet, Louis Marchand, appeared in print. His description of Napoleon in the months before his death led Sten Forshufvud to put forward other causes for his death, including deliberate arsenic poisoning, in a 1961 paper in Nature. Arsenic was used as a poison during the era because it was undetectable when administered over a long period. Forshufvud, in a 1978 book with Ben Weider, noted the emperor's body was found to be remarkably well-preserved when moved in 1840. Arsenic is a strong preservative, and therefore this supported the poisoning hypothesis. Forshufvud and Weider observed that Napoleon had attempted to quench abnormal thirst by drinking high levels of orgeat syrup that contained cyanide compounds in the almonds used for flavouring. They maintained that the potassium tartrate used in his treatment prevented his stomach from expellation of these compounds and that the thirst was a symptom of poisoning. Their hypothesis was that the calomel given to Napoleon became an overdose, which killed him and left behind extensive tissue damage.A 2007 article stated the type of arsenic found in Napoleon's hair shafts was mineral type, the most toxic, and according to toxicologist Patrick Kintz, this supported the conclusion his death was murder.
The wallpaper used in Longwood contained a high level of arsenic compound used for colouring by British manufacturers. The adhesive, which in the cooler British environment was innocuous, may have grown mould in the more humid climate and emitted the poisonous gas arsine. This theory has been ruled out as it does not explain the arsenic absorption patterns found in other analyses.
There have been modern studies which have supported the original autopsy finding. Researchers, in a 2008 study, analysed samples of Napoleon's hair from throughout his life, and from his family and other contemporaries. All samples had high levels of arsenic, approximately 100 times higher than the current average. According to these researchers, Napoleon's body was already heavily contaminated with arsenic as a boy, and the high arsenic concentration in his hair was not caused by intentional poisoning; people were constantly exposed to arsenic from glues and dyes throughout their lives.2007 and 2008 studies dismissed evidence of arsenic poisoning, and confirmed evidence of peptic ulcer and gastric cancer as the cause of death