coup de main
noun/ku də meɪn/ · /ku də mæn/
Etymology Borrowed from French coup de main.
1
A sudden development or action carried out to surprise an enemy.
- That which of all things he most dreaded was that he should be out-generalled by Mr. Slope; and just at present it appeared probable that Mr. Slope would turn his flank, steal a march on him, cut off his provisions, carry his strong town by a coup de main, and at last beat him thoroughly in a regular pitched battle.1857, Anthony Trollope, Barchester Towers, volume II, →ISBN, page 78: