Approximately 7,000 Prussian soldiers were killed or wounded at Waterloo. Historical summaries commonly give the Prussian army’s losses as about 6,600 to 7,000 casualties, making 7,000 the standard rounded answer.
The Prussians, commanded by Field Marshal Gebhard Leberecht von Blücher, played a decisive role in the battle. Napoleon had defeated the Prussians at Ligny two days earlier and believed they were retreating away from the main action. Instead, Blücher promised Wellington support and marched his troops toward Waterloo.
Prussian formations began arriving on Napoleon’s eastern flank during the afternoon of 18 June. Their attacks around Plancenoit stretched the French army and prevented Napoleon from concentrating all his strength against Wellington. The final Prussian advance helped turn the French retreat into a rout.
Exact totals vary because some accounts include missing soldiers alongside those killed and wounded. That is why figures may appear as 6,600, 7,000 or slightly more, but 7,000 is the accepted approximate figure for a quiz answer.