At Pavia, the french gendarmes were surrounded by an overwhelming number of pikemen and other infantry (who also were protected by the forrested terrain). Their horses were killed by pikes, and the riders were finished off by arqebusers who fired their wepons at point-blank range - piercing the armour at vurnable gaps
Charges of heavy cavalry were successful when used at the right moment - something that ardent european knights often tended to forget. Against well-drilled infantry with polearms they were inneffective throughout the middle ages. The battle of Hastings is often hailed as the first triumph of the knight in Europe. In fact the saxon huskarls were only routed after they had broken up from their initial defensive formation, which successfully had resisted the norman horse.
It's true that knights often suffered defeats. The reason is that the noblemen themselves thought they were invincible, and foolishly plunged themselves into hot-headed charges that were doomed to fail - such as at Bannockburn, Coutrai, Morgarten and many other occasions. The british though soon learned how to use their knights effectively, and won many victories in the hundred years war and against the scots during the 14th century - when the english knights were used together with infantry. After Bannockburn english knights seldomly charged a well prepared enemy. At Crcy 1346, most french casualties were in fact inflicted by the english knights - not the longbowmen. The english longbowmen and dismounted knights first decimated the french knights from a defensive formation, but once the french knights broke and fled the english knights mounted on fresh horses and charged the disorganised french infantry. The french routed and a horrible slaughter followed as the english knights rode down almost 10 000 french
But when the french learned how to combine infantry and cavalry they too were successful against the english during the last stages of the hundred year's war n the 15th century - at Jargeau, Patay, Formigny and Castillon their knights successfullt routed english armies
Edited by Mangudai