Never interrupt your enemy when he is making a mistake.

The crisp modern one-liner most people share — "Never interrupt your enemy when he is making a mistake" — is not found verbatim in anything Napoleon himself wrote or in any newspaper from his lifetime, yet the sentiment is authentically his. It traces to a real moment before the Battle of Austerlitz in December 1805: as his marshals begged to attack the maneuvering Allied columns, Napoleon reportedly held them back, saying (in Archibald Alison's 1836 history) that "when the enemy is making a false movement we must take good care not to interrupt him." Nineteenth-century military and biographical writers repeated the anecdote in slightly different wording — Twemlow's 1855 tactics manual and an 1852 profile of Marshal Soult among them — and the streamlined "making a mistake" phrasing hardened into a maxim credited to Napoleon by 1888. We found no competing author and nothing predating him, so the attribution is sound; what is missing is a primary source for the polished modern wording, which appears to be a later condensation of his genuine remark rather than a direct quotation.