Battle of Crécy
On 26 August 1346 the English army of Edward III, led by its longbowmen, routed the French knights.

Loyset Liédet · Public domain · Source
Edward III, who had landed in Normandy and was marching north, drew up his army on a ridge near Crécy. Philip VI’s French army was far larger, but the Genoese crossbowmen in the van broke under the rapid shooting of the English longbowmen, and the knights who charged again and again behind them fell to arrows and infantry. The English are said to have used early cannon as well.
The defeat of mounted knights by the bows of common foot soldiers showed that the feudal army built around knights was in decline. Edward III went on to besiege Calais, which he took the following year.