To set the Thames on fire
Preserved but no longer current.
See THAMES. We do not fire first, gentlemen. According to tradition this very chivalrous reply was made to Lord Charles Hay (in command of the Guards) at the opening of the battle of Fontenoy (1745) by the French Marquis d'Auteroche after the former had advanced from the British lines and invited the French commander to order his men to fire.
Era: ca. 1898 (Victorian)
Sources & notes
Reproduced from Brewer’s Dictionary of Phrase and Fable (1898 edition, public domain; archive.org, retrieved 2026-07-31; OCR text, minor errors possible). Reflects the scholarship and attitudes of its era.
Common questions
What does “To set the Thames on fire” mean?
See THAMES. We do not fire first, gentlemen. According to tradition this very chivalrous reply was made to Lord Charles Hay (in command of the Guards) at the opening of the battle of Fontenoy (1745) by the French Marquis d'Auteroche after the former had advanced from the British lines and invited the French commander to order his men to fire.
Is “To set the Thames on fire” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.