Definition from Wiktionary, the free dictionary
beau geste (plural beaux gestes)
- A gracious gesture, noble in form but often futile or meaningless in substance.
- "In a magnificent beau geste, the destroyer, hopelessly trapped, turned as if to flee, threw out a smoke screen, and when the [enemy ship] charged into it, rammed her at flank speed..." --William Manchester, The Last Lion Vol. 2, page 635