Johannes Ambrosius Rosenstrauch (1768-1835), a German immigrant to Russia and owner of a fashion store, was an eyewitness to the occupation of Moscow by Napoleon. His memoir of these events, hitherto unknown to historians, is here published for the first time both in the original German and in Russian translation. It tells a dramatic story of the horrors of war, the cruelty of the Napoleonic army, the class conflicts among Russians, and the burning of Moscow. The memoir is preceded by a Russian-language biography (summarized in English) that describes the author’s life in Germany and Russia, during which he was an actor, merchant, freemason, and Lutheran pastor, and became acquainted with leading figures of the Russian imperial court. Rosenstrauch is interesting both as a memoirist of the Napoleonic Wars and as a colorful figure whose life reflects many aspects of the social and cultural history of the period.