Wavre (Hundred Days).
Fought June 18, 1815, between the French, under Grouchy, and the Prussians, 27,000 strong, under Thielmann, who had been entrusted by Blucher with the task of containing Grouchy, while the main Prussian army marched on Waterloo. Grouchy, who was anxiously expected at Waterloo, mistook his instructions, and wasted the day in attacking Thielmann, whom he defeated, but uselessly.